Do not detect AES-NI support if disabled by configure.
* src/hwfeatures.c (detect_ia32_gnuc): Detect AESNI support only if that support has been enabled.
We better do not try to detect AESNI support if the support has been
disabled in the configure run. Disabling the support might have been
done due to problem with the AESNI support on a certain platform and
we can't exclude problem for sure with the detection code either.