cmd/asm: uncomment tests for PCMPESTRI, PHMINPOSUW

Instructions are implemented in the following revisions:
PCMPESTRI - https://golang.org/cl/22337
PHMINPOSUW - https://golang.org/cl/18853

It is unknown when x86test will be updated/re-run, but tests are useful
to check which x86 instructions are not yet supported.
As an example of tool that uses this information, there is Damien
Lespiau x86db.

Part of the mission to add missing amd64 SSE4 instructions to Go asm.

Change-Id: I512ff26040f47a0976b3e37000fb1f37eac5b762
Reviewed-on: https://go-review.googlesource.com/55830
Run-TryBot: Ilya Tocar <ilya.tocar@intel.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ilya Tocar <ilya.tocar@intel.com>

src/cmd/asm/internal/asm/testdata/amd64enc.s

@@ -3467,14 +3467,14 @@ TEXT asmtest(SB),DUPOK|NOSPLIT,$0
 	PCMPEQW (R11), X11                      // 66450f751b
 	PCMPEQW X2, X11                         // 66440f75da
 	PCMPEQW X11, X11                        // 66450f75db
-	//TODO: PCMPESTRI $7, (BX), X2          // 660f3a611307
-	//TODO: PCMPESTRI $7, (R11), X2         // 66410f3a611307
-	//TODO: PCMPESTRI $7, X2, X2            // 660f3a61d207
-	//TODO: PCMPESTRI $7, X11, X2           // 66410f3a61d307
-	//TODO: PCMPESTRI $7, (BX), X11         // 66440f3a611b07
-	//TODO: PCMPESTRI $7, (R11), X11        // 66450f3a611b07
-	//TODO: PCMPESTRI $7, X2, X11           // 66440f3a61da07
-	//TODO: PCMPESTRI $7, X11, X11          // 66450f3a61db07
+	PCMPESTRI $7, (BX), X2                  // 660f3a611307
+	PCMPESTRI $7, (R11), X2                 // 66410f3a611307
+	PCMPESTRI $7, X2, X2                    // 660f3a61d207
+	PCMPESTRI $7, X11, X2                   // 66410f3a61d307
+	PCMPESTRI $7, (BX), X11                 // 66440f3a611b07
+	PCMPESTRI $7, (R11), X11                // 66450f3a611b07
+	PCMPESTRI $7, X2, X11                   // 66440f3a61da07
+	PCMPESTRI $7, X11, X11                  // 66450f3a61db07
 	//TODO: PCMPESTRM $7, (BX), X2          // 660f3a601307
 	//TODO: PCMPESTRM $7, (R11), X2         // 66410f3a601307
 	//TODO: PCMPESTRM $7, X2, X2            // 660f3a60d207
@@ -3671,14 +3671,14 @@ TEXT asmtest(SB),DUPOK|NOSPLIT,$0
 	//TODO: PHADDW (R11), X11               // 66450f38011b
 	//TODO: PHADDW X2, X11                  // 66440f3801da
 	//TODO: PHADDW X11, X11                 // 66450f3801db
-	//TODO: PHMINPOSUW (BX), X2             // 660f384113
-	//TODO: PHMINPOSUW (R11), X2            // 66410f384113
-	//TODO: PHMINPOSUW X2, X2               // 660f3841d2
-	//TODO: PHMINPOSUW X11, X2              // 66410f3841d3
-	//TODO: PHMINPOSUW (BX), X11            // 66440f38411b
-	//TODO: PHMINPOSUW (R11), X11           // 66450f38411b
-	//TODO: PHMINPOSUW X2, X11              // 66440f3841da
-	//TODO: PHMINPOSUW X11, X11             // 66450f3841db
+	PHMINPOSUW (BX), X2                     // 660f384113
+	PHMINPOSUW (R11), X2                    // 66410f384113
+	PHMINPOSUW X2, X2                       // 660f3841d2
+	PHMINPOSUW X11, X2                      // 66410f3841d3
+	PHMINPOSUW (BX), X11                    // 66440f38411b
+	PHMINPOSUW (R11), X11                   // 66450f38411b
+	PHMINPOSUW X2, X11                      // 66440f3841da
+	PHMINPOSUW X11, X11                     // 66450f3841db
 	//TODO: PHSUBD (BX), M2                 // 0f380613
 	//TODO: PHSUBD (R11), M2                // 410f380613
 	//TODO: PHSUBD M2, M2                   // 0f3806d2