compiler: drop CONFIG_HAVE_LONG_LONG and require long long support

[xiaoxiang781216]

Summary

CONFIG_HAVE_LONG_LONG is set to 1 for every modern toolchain that NuttX
supports, so the indirection is no longer useful. Drop the config knob and
the surrounding #ifdef/#ifndef CONFIG_HAVE_LONG_LONG ladders, and treat
long long as unconditionally available across the OS.

Impact

• include/nuttx/compiler.h: remove all #define/#undef of the macro and
  the dead #ifndef CONFIG_HAVE_LONG_LONG block at the end of the file.
• Headers and sources under include/, drivers/, fs/, libs/, sched/:
  unwrap #ifdef CONFIG_HAVE_LONG_LONG (keep then-branch, drop else-branch),
  drop #ifndef CONFIG_HAVE_LONG_LONG blocks (always dead).
• libs/libc/libc.csv: drop unconditional/now-dead rows referencing the
  macro and clear the column where the condition was always true.
• libs/libc/fixedmath/lib_fixedmath.c: removed (entire file body was the
  dead #ifndef branch).
• Documentation/applications/netutils/ntpclient/index.rst: drop the bullet.

Testing

• tools/checkpatch.sh -f is clean on all changed files (only pre-existing
  long-line / case-on-new-line errors remain in untouched code).

Companion PR

apache/nuttx-apps companion PR is required for the apps/-side preprocessor
clean-up.

[Copilot]

Pull request overview

This PR removes the CONFIG_HAVE_LONG_LONG configuration knob and treats long long (and related 64-bit integer types) as unconditionally available across NuttX, simplifying headers/sources that previously had alternate code paths.

Changes:

• Remove CONFIG_HAVE_LONG_LONG definitions/undefs and unwrap dependent preprocessor conditionals across the tree.
• Make long long-based APIs and implementations (printf/scanf, crc64, fixedmath helpers, etc.) unconditional.
• Clean up ancillary build metadata/docs impacted by the removal (e.g., fixedmath build files, ntpclient docs, libc API CSV).

Reviewed changes

Copilot reviewed 46 out of 46 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
sched/irq/irq_procfs.c	Removes CONFIG_HAVE_LONG_LONG gating and updates procfs IRQ output note.
sched/clock/clock.h	Drops dead CONFIG_SYSTEM_TIME64 undef tied to CONFIG_HAVE_LONG_LONG.
libs/libm/libm/lib_llroundl.c	Makes llroundl availability depend only on long double support.
libs/libm/libm/lib_llroundf.c	Makes llroundf unconditional.
libs/libm/libm/lib_llround.c	Makes llround depend only on double support.
libs/libc/string/lib_vikmemcpy.c	Removes long-long-based config undef guard for 64-bit memcpy option.
libs/libc/string/lib_memset.c	Removes long-long-based config undef guard for 64-bit memset option.
libs/libc/string/lib_flsll.c	Makes flsll implementation unconditional.
libs/libc/string/lib_ffsll.c	Makes ffsll implementation unconditional.
libs/libc/stream/lib_ultoa_invert.h	Removes long-long availability gating for CONFIG_LIBC_LONG_LONG validity comment/undef.
libs/libc/stream/lib_libvsprintf.c	Unwraps long long handling paths in printf implementation.
libs/libc/stream/lib_libvscanf.c	Unwraps long long handling paths in scanf implementation.
libs/libc/stream/lib_libbsprintf.c	Unwraps long long handling in binary sprintf helper.
libs/libc/stdlib/lib_strtoull.c	Makes strtoull implementation unconditional.
libs/libc/stdlib/lib_strtoll.c	Makes strtoll implementation unconditional.
libs/libc/stdlib/lib_strtold.c	Removes non-long-long fallback typedef/macro path.
libs/libc/stdlib/lib_rand48.c	Unwraps rand48 family implementation using 64-bit math.
libs/libc/stdlib/lib_lldiv.c	Makes lldiv unconditional.
libs/libc/stdlib/lib_llabs.c	Makes llabs unconditional.
libs/libc/stdlib/lib_atoll.c	Makes atoll unconditional.
libs/libc/misc/lib_crc64emac.c	Makes CRC64-EMAC implementation unconditional.
libs/libc/misc/lib_crc64.c	Makes CRC64 implementation unconditional.
libs/libc/lzf/lzf_c.c	Removes non-uint64_t fallback type for compression offset variable.
libs/libc/libc.csv	Removes/updates CONFIG_HAVE_LONG_LONG conditions in exported libc symbol list.
libs/libc/inttypes/lib_strtoimax.c	Makes strtoimax implementation unconditional.
libs/libc/fixedmath/lib_ubsqrt.c	Makes ub32sqrtub16 implementation unconditional.
libs/libc/fixedmath/lib_fixedmath.c	Removes dead fixedmath fallback file body (entire file removed).
libs/libc/fixedmath/Make.defs	Drops removed fixedmath source from build list.
libs/libc/fixedmath/CMakeLists.txt	Drops removed fixedmath source from build list.
include/sys/epoll.h	Makes epoll_data_t include u64 member unconditionally.
include/sys/endian.h	Makes 64-bit endian swap helpers/macros unconditional.
include/strings.h	Makes ffsll/flsll declarations unconditional (and related builtin macros).
include/stdlib.h	Makes long-long-related stdlib prototypes unconditional.
include/stddef.h	Makes max_align_t include a long long member unconditionally.
include/nuttx/lib/stdbit.h	Removes CONFIG_HAVE_LONG_LONG from builtin requirement checks (now unconditional 64-bit builtin requirement).
include/nuttx/lib/math32.h	Removes long-long gating around 64-bit helper macros/implementations.
include/nuttx/lib/math.h	Makes llround*/llrint* declarations unconditional.
include/nuttx/crc64.h	Makes crc64 API definitions/prototypes unconditional.
include/nuttx/compiler.h	Removes all CONFIG_HAVE_LONG_LONG define/undef logic and dependent dead guards.
include/nuttx/clock.h	Drops dead CONFIG_SYSTEM_TIME64 undef tied to CONFIG_HAVE_LONG_LONG.
include/nuttx/audio/audio.h	Makes 64-bit capability control member unconditional.
include/fixedmath.h	Removes long-long gating and non-long-long fallback declarations/macros.
include/cxx/cstdlib	Makes C++ std:: imports for long-long stdlib APIs unconditional.
fs/spiffs/src/spiffs.h	Removes off_t fallback and makes media_size always off64_t.
drivers/note/note_driver.c	Unwraps long long handling in note printf capture logic.
Documentation/applications/netutils/ntpclient/index.rst	Removes documentation requirement for CONFIG_HAVE_LONG_LONG.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.