all: use more precise build tags

s/!gccgo/gc/ in files which use gc-syntax assembly.

Change-Id: Ifdadb62edd1210ebc70e7cd415648b752afaf067
Reviewed-on: https://go-review.googlesource.com/c/go/+/269957
Reviewed-by: Than McIntosh <thanm@google.com>
Trust: David Chase <drchase@google.com>
Trust: Matthew Dempsky <mdempsky@google.com>

misc/cgo/test/testdata/issue9400/asm_386.s

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 

misc/cgo/test/testdata/issue9400/asm_amd64x.s

@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // +build amd64 amd64p32
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 

misc/cgo/test/testdata/issue9400/asm_arm.s

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 

misc/cgo/test/testdata/issue9400/asm_arm64.s

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 

misc/cgo/test/testdata/issue9400/asm_mips64x.s

@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // +build mips64 mips64le
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 

misc/cgo/test/testdata/issue9400/asm_mipsx.s

@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // +build mips mipsle
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 

misc/cgo/test/testdata/issue9400/asm_ppc64x.s

@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // +build ppc64 ppc64le
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 

misc/cgo/test/testdata/issue9400/asm_riscv64.s

@@ -3,7 +3,7 @@
 // license that can be found in the LICENSE file.
 
 // +build riscv64
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 

misc/cgo/test/testdata/issue9400/asm_s390x.s

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 

misc/cgo/testshared/testdata/depBase/asm.s

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !gccgo
+// +build gc
 
 #include "textflag.h"
 

misc/cgo/testshared/testdata/depBase/stubs.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build !gccgo
+// +build gc
 
 package depBase
 

src/cmd/dist/util_gc.go

@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-//go:build !gccgo
-// +build !gccgo
+//go:build gc
+// +build gc
 
 package main
 

src/cmd/go/testdata/script/build_overlay.txt

@@ -238,7 +238,7 @@ void say_hello();
 
 void say_hello() { puts("hello cgo\n"); fflush(stdout); }
 -- m/overlay/asm_gc.s --
-// +build !gccgo
+// +build gc
 
 TEXT ·foo(SB),0,$0
 	RET