* config.gcc (x86_64-*-*): Install mmintrin.h and xmmintrin.h.

for testsuite:
	* gcc.dg/i386-mmx-1.c: Also run on x86-64.
	* gcc.dg/i386-mmx-2.c: Likewise.
	* gcc.dg/i386-sse-1.c: Likewise.
	* gcc.dg/i386-sse-2.c: Likewise.
	* gcc.dg/i386-sse-3.c: Likewise.

From-SVN: r48864