Add IA MCU support to x86intrin.h

Add IA MCU support to x86intrin.h

x86intrin.h has useful intrinsics for instructions for IA MCU.  This
patch adds __iamcu__ check to x86intrin.h and ia32intrin.h.

gcc/

	PR target/66746.
	* config/i386/ia32intrin.h (__crc32b): Don't define if __iamcu__
	is defined.
	(__crc32w): Likewise.
	(__crc32d): Likewise.
	(__rdpmc): Likewise.
	(__rdtscp): Likewise.
	(_rdpmc): Likewise.
	(_rdtscp): Likewise.
	* config/i386/x86intrin.h: Only include ia32intrin.h if __iamcu__
	is defined.

gcc/testsuite/

	PR target/66746.
	* gcc.target/i386/pr66746.c: New file.

From-SVN: r225376