linux-user: Move PRAGMA_DISABLE_PACKED_WARNING to compiler.h

Replace the slightly older version of this in include/qemu/compiler.h
that was commit as part of bsd-user changes with the newer one from
linux-user. bsd-user has no regreassions with this.

Signed-off-by: Warner Losh <imp@bsdimp.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

include/qemu/compiler.h

@@ -31,17 +31,13 @@
  *   functions than host-endian unaligned load/store plus tswapN.
  * - The pragmas are necessary only to silence a clang false-positive
  *   warning: see https://bugs.llvm.org/show_bug.cgi?id=39113 .
- * - We have to disable -Wpragmas warnings to avoid a complaint about
- *   an unknown warning type from older compilers that don't know about
- *   -Waddress-of-packed-member.
  * - gcc has bugs in its _Pragma() support in some versions, eg
  *   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83256 -- so we only
  *   include the warning-suppression pragmas for clang
  */
-#ifdef __clang__
+#if defined(__clang__) && __has_warning("-Waddress-of-packed-member")
 #define PRAGMA_DISABLE_PACKED_WARNING                                   \
     _Pragma("GCC diagnostic push");                                     \
-    _Pragma("GCC diagnostic ignored \"-Wpragmas\"");                    \
     _Pragma("GCC diagnostic ignored \"-Waddress-of-packed-member\"")
 
 #define PRAGMA_REENABLE_PACKED_WARNING          \

linux-user/qemu.h

@@ -193,32 +193,6 @@ static inline bool access_ok(CPUState *cpu, int type,
    These are usually used to access struct data members once the struct has
    been locked - usually with lock_user_struct.  */
 
-/*
- * Tricky points:
- * - Use __builtin_choose_expr to avoid type promotion from ?:,
- * - Invalid sizes result in a compile time error stemming from
- *   the fact that abort has no parameters.
- * - It's easier to use the endian-specific unaligned load/store
- *   functions than host-endian unaligned load/store plus tswapN.
- * - The pragmas are necessary only to silence a clang false-positive
- *   warning: see https://bugs.llvm.org/show_bug.cgi?id=39113 .
- * - gcc has bugs in its _Pragma() support in some versions, eg
- *   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83256 -- so we only
- *   include the warning-suppression pragmas for clang
- */
-#if defined(__clang__) && __has_warning("-Waddress-of-packed-member")
-#define PRAGMA_DISABLE_PACKED_WARNING                                   \
-    _Pragma("GCC diagnostic push");                                     \
-    _Pragma("GCC diagnostic ignored \"-Waddress-of-packed-member\"")
-
-#define PRAGMA_REENABLE_PACKED_WARNING          \
-    _Pragma("GCC diagnostic pop")
-
-#else
-#define PRAGMA_DISABLE_PACKED_WARNING
-#define PRAGMA_REENABLE_PACKED_WARNING
-#endif
-
 #define __put_user_e(x, hptr, e)                                            \
     do {                                                                    \
         PRAGMA_DISABLE_PACKED_WARNING;                                      \