wasi-sdk-5

wasi-sysroot changes:

Makefile: Don't mix phony targets with directory names
delete a space in predefined-macros.txt
replace some macros with its builtins analogs
rename printf_no_Lf to __small_printf
Define TIME_UTC to be 1.
Define CLOCKS_PER_SEC to have type clock_t.
Optimize lseek in the `tell` case.
Say "wasm32-wasi" rather than "wasm32-unknown-wasi".
Declare getentropy in <sys/random.h>
Disable unused fields in FILE and __libc.
Add vfwprintf.c to the printscan list.
Implement FD_SET, FD_CLR, etc.
Remove capsicum.h; WASI libc doesn't support that API, even internally.
Make calloc set ENOMEM when failing due to overflow.
Make the strerror message for ESUCCESS (0) be "Success".
Implement reallocarray.
Update README.md
Add missing asctime symbol
Fix floatscan no long double usage (#21)
Remove the Linux-specific <sys/signalfd.h> header.
Declare getrusage.
Format changes to musl code to fit musl's style.
Fixes #20
gitignore build

sdk changes:
Say "wasm32-wasi" instead of "wasm32-unknown-wasi" in wasi-sdk.
Distribute versions of config.sub and config.guess with wasm and wasi
support. Fixes #16.

Create a tarball of the clang-rt builtins in tar_from_installation.sh
These builtins are required to use WASI with an existing clang
installation.