targets: rename qemu target to cortex-m-qemu

The target is intended to emulate the Cortex-M, not to be a generic QEMU
target.

main_test.go

@@ -50,7 +50,7 @@ func TestCompiler(t *testing.T) {
 	}
 
 	t.Run("EmulatedCortexM3", func(t *testing.T) {
-		runPlatTests("qemu", matches, t)
+		runPlatTests("cortex-m-qemu", matches, t)
 	})
 
 	if runtime.GOOS == "linux" {
@@ -76,7 +76,7 @@ func runPlatTests(target string, matches []string, t *testing.T) {
 			}
 		case target == "":
 			// run all tests on host
-		case target == "qemu":
+		case target == "cortex-m-qemu":
 			// all tests are supported
 		default:
 			// cross-compilation of cgo is not yet supported

src/runtime/runtime_cortexm_qemu.go

@@ -1,4 +1,4 @@
-// +build qemu
+// +build cortexm,qemu
 
 package runtime
 

targets/cortex-m-qemu.json

@@ -8,7 +8,7 @@
 	],
 	"linkerscript": "targets/lm3s6965.ld",
 	"extra-files": [
-		"targets/qemu.s"
+		"targets/cortex-m-qemu.s"
 	],
 	"emulator": ["qemu-system-arm", "-machine", "lm3s6965evb", "-semihosting", "-nographic", "-kernel"]
 }

targets/cortex-m-qemu.s

@@ -1,5 +1,5 @@
 // Generic Cortex-M interrupt vector.
-// This vector is used by the QEMU target.
+// This vector is used by the Cortex-M QEMU target.
 
 .syntax unified