Thanks for the fix, Adhemerval Zanella.
I assume you would fix this in other files too, for example I think a similar
patch is needed for posix/fnmatch.c.
fnmatch.c:67:26: error: "__clang_major__" is not defined [-Werror=undef]
# if (__GNUC__ >= 7) || (__clang_major__ >= 10)
After this commit [1], I am seeing -Werror=undef when bootstapping glibc on
aarch64-none-linux-gnu :
In file included from regex.c:70:0:
regex_internal.h:852:26: error: "__clang_major__" is not defined [-Werror=undef]
# if (__GNUC__ >= 7) || (__clang_major__ >= 10)
