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/builder.go

@@ -45,7 +45,6 @@ var (
 				`find $outDir -name "*.class" > $out`,
 			Rspfile:        "$out.rsp",
 			RspfileContent: "$in",
-			Description:    "javac $outDir",
 		},
 		"javacCmd", "javacFlags", "bootClasspath", "classpath", "outDir")
 
@@ -53,7 +52,6 @@ var (
 		blueprint.RuleParams{
 			Command:     `$jarCmd -o $out $jarArgs`,
 			CommandDeps: []string{"$jarCmd"},
-			Description: "jar $out",
 		},
 		"jarCmd", "jarArgs")
 
@@ -63,7 +61,6 @@ var (
 				`$dxCmd --dex --output=$outDir $dxFlags $in || ( rm -rf "$outDir"; exit 41 ) && ` +
 				`find "$outDir" -name "classes*.dex" > $out`,
 			CommandDeps: []string{"$dxCmd"},
-			Description: "dex $out",
 		},
 		"outDir", "dxFlags")
 
@@ -71,7 +68,6 @@ var (
 		blueprint.RuleParams{
 			Command:     "java -jar $jarjarCmd process $rulesFile $in $out",
 			CommandDeps: []string{"$jarjarCmd", "$rulesFile"},
-			Description: "jarjar $out",
 		},
 		"rulesFile")
 
@@ -81,7 +77,6 @@ var (
 				`find $outDir -name "*.class" > $classFile && ` +
 				`find $outDir -type f -a \! -name "*.class" -a \! -name "MANIFEST.MF" > $resourceFile || ` +
 				`(rm -rf $outDir; exit 42)`,
-			Description: "extract java prebuilt $outDir",
 		},
 		"outDir", "classFile", "resourceFile")
 )
@@ -122,10 +117,11 @@ func TransformJavaToClasses(ctx android.ModuleContext, srcFiles android.Paths, s
 	deps = append(deps, srcFileLists...)
 
 	ctx.ModuleBuild(pctx, android.ModuleBuildParams{
-		Rule:      javac,
-		Output:    classFileList,
-		Inputs:    srcFiles,
-		Implicits: deps,
+		Rule:        javac,
+		Description: "javac",
+		Output:      classFileList,
+		Inputs:      srcFiles,
+		Implicits:   deps,
 		Args: map[string]string{
 			"javacFlags":    javacFlags,
 			"bootClasspath": flags.bootClasspath,
@@ -156,9 +152,10 @@ func TransformClassesToJar(ctx android.ModuleContext, classes []jarSpec,
 	}
 
 	ctx.ModuleBuild(pctx, android.ModuleBuildParams{
-		Rule:      jar,
-		Output:    outputFile,
-		Implicits: deps,
+		Rule:        jar,
+		Description: "jar",
+		Output:      outputFile,
+		Implicits:   deps,
 		Args: map[string]string{
 			"jarArgs": strings.Join(jarArgs, " "),
 		},
@@ -174,9 +171,10 @@ func TransformClassesJarToDex(ctx android.ModuleContext, classesJar android.Path
 	outputFile := android.PathForModuleOut(ctx, "dex.filelist")
 
 	ctx.ModuleBuild(pctx, android.ModuleBuildParams{
-		Rule:   dx,
-		Output: outputFile,
-		Input:  classesJar,
+		Rule:        dx,
+		Description: "dx",
+		Output:      outputFile,
+		Input:       classesJar,
 		Args: map[string]string{
 			"dxFlags": flags.dxFlags,
 			"outDir":  outDir.String(),
@@ -202,9 +200,10 @@ func TransformDexToJavaLib(ctx android.ModuleContext, resources []jarSpec,
 	jarArgs = append(jarArgs, dexJarSpec.soongJarArgs())
 
 	ctx.ModuleBuild(pctx, android.ModuleBuildParams{
-		Rule:      jar,
-		Output:    outputFile,
-		Implicits: deps,
+		Rule:        jar,
+		Description: "jar",
+		Output:      outputFile,
+		Implicits:   deps,
 		Args: map[string]string{
 			"jarArgs": strings.Join(jarArgs, " "),
 		},
@@ -216,10 +215,11 @@ func TransformDexToJavaLib(ctx android.ModuleContext, resources []jarSpec,
 func TransformJarJar(ctx android.ModuleContext, classesJar android.Path, rulesFile android.Path) android.Path {
 	outputFile := android.PathForModuleOut(ctx, "classes-jarjar.jar")
 	ctx.ModuleBuild(pctx, android.ModuleBuildParams{
-		Rule:     jarjar,
-		Output:   outputFile,
-		Input:    classesJar,
-		Implicit: rulesFile,
+		Rule:        jarjar,
+		Description: "jarjar",
+		Output:      outputFile,
+		Input:       classesJar,
+		Implicit:    rulesFile,
 		Args: map[string]string{
 			"rulesFile": rulesFile.String(),
 		},
@@ -236,9 +236,10 @@ func TransformPrebuiltJarToClasses(ctx android.ModuleContext,
 	resourceFileList := android.PathForModuleOut(ctx, "extracted/resources.list")
 
 	ctx.ModuleBuild(pctx, android.ModuleBuildParams{
-		Rule:    extractPrebuilt,
-		Outputs: android.WritablePaths{classFileList, resourceFileList},
-		Input:   prebuilt,
+		Rule:        extractPrebuilt,
+		Description: "extract classes",
+		Outputs:     android.WritablePaths{classFileList, resourceFileList},
+		Input:       prebuilt,
 		Args: map[string]string{
 			"outDir":       classDir.String(),
 			"classFile":    classFileList.String(),