Disable many _GL_CXXALIASWARN on all platforms other than glibc systems. Reported by Christian Biesinger <cbiesinger@google.com> in <https://lists.gnu.org/archive/html/bug-gnulib/2019-11/msg00066.html>. * lib/fnmatch.in.h (fnmatch): Disable _GL_CXXALIASWARN invocation on non-glibc systems. * lib/locale.in.h (localeconv, setlocale): Likewise. * lib/math.in.h (cbrt, ceil, copysign, exp2, expm1, floor, fma, fmod, frexp, hypot, ilogb, log, log10, log1p, log2, logb, modf, remainder, rint, round, trunc): Likewise. * lib/monetary.in.h (strfmon_l): Likewise. * lib/pthread.in.h (pthread_mutexattr_getrobust, pthread_mutexattr_setrobust, pthread_mutex_lock, pthread_spin_init, pthread_spin_lock, pthread_spin_trylock, pthread_spin_unlock, pthread_spin_destroy): Likewise. * lib/signal.in.h (raise, signal): Likewise. * lib/stdio.in.h (fclose, fflush, fgetc, fgets, fopen, fprintf, fputc, fputs, fread, freopen, fscanf, fseek, ftell, fwrite, getc, getchar, perror, printf, putc, putchar, puts, remove, rename, scanf, sprintf, tmpfile, vfprintf, vprintf, vsprintf): Likewise. * lib/stdlib.in.h (calloc, malloc, mbtowc, realloc, strtod, wctomb): Likewise. * lib/string.in.h (memchr, strncat, strpbrk, strstr, strerror): Likewise. * lib/time.in.h (mktime, localtime, ctime, strftime): Likewise. * lib/wchar.in.h (btowc, wctob, mbsinit, mbrtowc, mbrlen, mbsrtowcs, wcrtomb, wcsrtombs, wmemchr, wmemcmp, wmemcpy, wmemmove, wmemset, wcslen, wcscpy, wcsncpy, wcscat, wcsncat, wcscmp, wcsncmp, wcscoll, wcsxfrm, wcschr, wcsrchr, wcscspn, wcsspn, wcspbrk, wcsstr, wcstok, wcsftime): Likewise. * lib/wctype.in.h (iswblank, wctrans, towctrans): Likewise.