Implement C23 const-preserving standard library macros

[Andreas Schwab]

This now breaks the build of binutils:

In file included from /usr/include/features.h:540,
                 from /usr/include/dlfcn.h:22,
                 from ../../../gprofng/libcollector/iolib.c:22:
../../../gprofng/libcollector/iolib.c: In function ‘is_not_the_log_file’:
../../../gprofng/libcollector/iolib.c:898:18: error: expected identifier before ‘_Generic’
  898 |   if (CALL_UTIL (strstr)(fname, SP_LOG_FILE) == NULL)
      |                  ^~~~~~
../../../gprofng/libcollector/iolib.c:898:7: note: in expansion of macro ‘CALL_UTIL’
  898 |   if (CALL_UTIL (strstr)(fname, SP_LOG_FILE) == NULL)
      |       ^~~~~~~~~
make[5]: *** [Makefile:648: libgp_collector_la-iolib.lo] Error 1

where CALL_UTIL is defined as:

#define CALL_UTIL(x) __collector_util_funcs.x

-- 
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
"And now for something completely different."