autoconf: update check for gcc inlines
autoconf: update check for gcc inlines

Old versions of gcc didn't define either __GNUC_STDC_INLINE__ or
__GNUC_GNU_INLINE__, but imply the latter.

Signed-off-by: H. Peter Anvin (Intel) <8a453bad9912ffe59bc0f0b8abe03df9be19379e@zytor.com>

techkey/nasm,techkey/nasm,techkey/nasm,techkey/nasm,techkey/nasm