Reduce gcc build time by disabling libsanitizer

[shao-hua-li]

I found that by --disable-libsanitizer, the gcc compilation time would reduce significantly from 15min to less than 5min. This would also fix the old gcc build issue mentioned in #50

[thetheodor]

This can be done by passing an extra argument --additional-configure-flags='--disable-libsanitizer', e.g.:

ccbuilder build gcc master --additional-configure-flags="--disable-libsanitizer"

I didn't want to make this the default as there would be no way to re-enable it. Maybe instead of passing additional configure flags, a better way would be to allow replacing the whole set of configure flags/arguments, then the default doesn't matter