[rs6000] Add compatible implementations of x86 SSSE3 intrinsics

This is a follow-on to earlier commits for adding compatibility
implementations of x86 intrinsics for PPC64LE.  This is the first of
two patches.  This patch adds the 32 x86 intrinsics from
<tmmintrin.h> ("SSSE3").  (Patch 2/2 adds tests for these intrinsics,
and briefly describes the tests performed.)

gcc/ChangeLog:

2018-10-26  Paul A. Clarke  <pc@us.ibm.com>

	* config/rs6000/tmmintrin.h: New file.
	* config.gcc (powerpc*-*-*): Add tmmintrin.h to extra_headers.

From-SVN: r265542

gcc/ChangeLog

-2018-10-25  Paul A. Clarke  <pc@us.ibm.com>
+2018-10-26  Paul A. Clarke  <pc@us.ibm.com>
+
+	* config/rs6000/tmmintrin.h: New file.
+	* config.gcc (powerpc*-*-*): Add tmmintrin.h to extra_headers.
+
+2018-10-26  Paul A. Clarke  <pc@us.ibm.com>
 
 	* config/rs6000/mmintrin.h: Enable 32bit compilation.
 	* config/rs6000/xmmintrin.h: Likewise.

gcc/config.gcc

@@ -485,7 +485,7 @@ powerpc*-*-*)
 	extra_headers="${extra_headers} bmi2intrin.h bmiintrin.h"
 	extra_headers="${extra_headers} xmmintrin.h mm_malloc.h emmintrin.h"
 	extra_headers="${extra_headers} mmintrin.h x86intrin.h"
-	extra_headers="${extra_headers} pmmintrin.h"
+	extra_headers="${extra_headers} pmmintrin.h tmmintrin.h"
 	extra_headers="${extra_headers} ppu_intrinsics.h spu2vmx.h vec_types.h si2vmx.h"
 	extra_headers="${extra_headers} amo.h"
 	case x$with_cpu in