Prettify soong ninja build descriptions

Descriptions currently look like:
[  0% 4/29328] cc out-soong/.intermediates/external/clang/lib/Sema/libclangSema/android_arm_armv7-a-neon_denver_static_core/obj/external/clang/lib/Sema/SemaCodeComplete.o

This is not very helpful - most of the characters are used to show the
output path, which contains useful information like target architecture,
but also contains most of the path to the source files twice, and less
useful information like the exact variant name used by soong.
Make the descriptions look like:
[  0% 3/29329] //external/clang/lib/Sema:libclangSema clang++ SemaTemplateInstantiate.cpp

This is //path/to/module:modulename tool relative/path/to/source/file

Test: builds, looks pretty
Change-Id: I3087aa7d4eb1860ef6239d77407b8b35445616d7

java/app_builder.go

@@ -34,7 +34,6 @@ var (
 				`-J $javaDir || ( rm -rf "$javaDir/*"; exit 41 ) && ` +
 				`find $javaDir -name "*.java" > $javaFileList`,
 			CommandDeps: []string{"$aaptCmd"},
-			Description: "aapt create R.java $out",
 		},
 		"aaptFlags", "publicResourcesFile", "proguardOptionsFile", "javaDir", "javaFileList")
 
@@ -42,7 +41,6 @@ var (
 		blueprint.RuleParams{
 			Command:     `rm -f $out && $aaptCmd package $aaptFlags -F $out`,
 			CommandDeps: []string{"$aaptCmd"},
-			Description: "aapt export package $out",
 		},
 		"aaptFlags", "publicResourcesFile", "proguardOptionsFile", "javaDir", "javaFileList")
 
@@ -51,7 +49,6 @@ var (
 			// TODO: add-jni-shared-libs-to-package
 			Command:     `cp -f $in $out.tmp && $aaptCmd package -u $aaptFlags -F $out.tmp && mv $out.tmp $out`,
 			CommandDeps: []string{"$aaptCmd"},
-			Description: "aapt package $out",
 		},
 		"aaptFlags")
 
@@ -59,7 +56,6 @@ var (
 		blueprint.RuleParams{
 			Command:     `java -jar $signapkCmd $certificates $in $out`,
 			CommandDeps: []string{"$signapkCmd"},
-			Description: "signapk $out",
 		},
 		"certificates")
 
@@ -68,7 +64,7 @@ var (
 			Command: "java -classpath $androidManifestMergerCmd com.android.manifmerger.Main merge " +
 				"--main $in --libs $libsManifests --out $out",
 			CommandDeps: []string{"$androidManifestMergerCmd"},
-			Description: "merge manifest files $out",
+			Description: "merge manifest files",
 		},
 		"libsManifests")
 )
@@ -87,9 +83,10 @@ func CreateResourceJavaFiles(ctx android.ModuleContext, flags []string,
 	proguardOptionsFile := android.PathForModuleOut(ctx, "proguard.options")
 
 	ctx.ModuleBuild(pctx, android.ModuleBuildParams{
-		Rule:      aaptCreateResourceJavaFile,
-		Outputs:   android.WritablePaths{publicResourcesFile, proguardOptionsFile, javaFileList},
-		Implicits: deps,
+		Rule:        aaptCreateResourceJavaFile,
+		Description: "aapt create R.java",
+		Outputs:     android.WritablePaths{publicResourcesFile, proguardOptionsFile, javaFileList},
+		Implicits:   deps,
 		Args: map[string]string{
 			"aaptFlags":           strings.Join(flags, " "),
 			"publicResourcesFile": publicResourcesFile.String(),
@@ -106,9 +103,10 @@ func CreateExportPackage(ctx android.ModuleContext, flags []string, deps android
 	outputFile := android.PathForModuleOut(ctx, "package-export.apk")
 
 	ctx.ModuleBuild(pctx, android.ModuleBuildParams{
-		Rule:      aaptCreateAssetsPackage,
-		Output:    outputFile,
-		Implicits: deps,
+		Rule:        aaptCreateAssetsPackage,
+		Description: "aapt export package",
+		Output:      outputFile,
+		Implicits:   deps,
 		Args: map[string]string{
 			"aaptFlags": strings.Join(flags, " "),
 		},
@@ -123,9 +121,10 @@ func CreateAppPackage(ctx android.ModuleContext, flags []string, jarFile android
 	resourceApk := android.PathForModuleOut(ctx, "resources.apk")
 
 	ctx.ModuleBuild(pctx, android.ModuleBuildParams{
-		Rule:   aaptAddResources,
-		Output: resourceApk,
-		Input:  jarFile,
+		Rule:        aaptAddResources,
+		Description: "aapt package",
+		Output:      resourceApk,
+		Input:       jarFile,
 		Args: map[string]string{
 			"aaptFlags": strings.Join(flags, " "),
 		},
@@ -139,9 +138,10 @@ func CreateAppPackage(ctx android.ModuleContext, flags []string, jarFile android
 	}
 
 	ctx.ModuleBuild(pctx, android.ModuleBuildParams{
-		Rule:   signapk,
-		Output: outputFile,
-		Input:  resourceApk,
+		Rule:        signapk,
+		Description: "signapk",
+		Output:      outputFile,
+		Input:       resourceApk,
 		Args: map[string]string{
 			"certificates": strings.Join(certificateArgs, " "),
 		},