build-host-gcc.sh: --disable-plugins --disable-plugin globally

 Until a GCC bug is fixed in plugin cross compilation, plugins
cannot be (canadian?) cross compiled:

 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50229

 I checked the released NDK r8d and the plugins are not enabled
on any GCC (configure lines all contain --disable-plugin)

Change-Id: I08e1f6b32ad62fdbfc26468a6c0968d4ec749dcd
1 file changed