Rename build.ninja with product name

Current build.ninja does not contain any product name, while other ninja
files (such as combined ninja) do. This change adds product name to the
build.ninja so it can be separated over multiple lunch targets

Bug: 277029044
Test: build succeeded and checked if out/soong/build.ninja has been
renamed

Change-Id: I16dc71f829fd76f01b98da0d509a8e0ef6f62fa9

android/config.go

@@ -80,9 +80,10 @@ type SoongBuildMode int
 
 type CmdArgs struct {
 	bootstrap.Args
-	RunGoTests  bool
-	OutDir      string
-	SoongOutDir string
+	RunGoTests     bool
+	OutDir         string
+	SoongOutDir    string
+	SoongVariables string
 
 	SymlinkForestMarker string
 	Bp2buildMarker      string
@@ -491,7 +492,7 @@ func NullConfig(outDir, soongOutDir string) Config {
 func NewConfig(cmdArgs CmdArgs, availableEnv map[string]string) (Config, error) {
 	// Make a config with default options.
 	config := &config{
-		ProductVariablesFileName: filepath.Join(cmdArgs.SoongOutDir, productVariablesFileName),
+		ProductVariablesFileName: cmdArgs.SoongVariables,
 
 		env: availableEnv,