Merge "Revert "Support per-module MakeVars""

cc/gen.go

@@ -24,6 +24,8 @@ import (
 )
 
 func init() {
+	pctx.SourcePathVariable("m4Cmd", "prebuilts/build-tools/${config.HostPrebuiltTag}/bin/m4")
+
 	pctx.HostBinToolVariable("aidlCmd", "aidl-cpp")
 	pctx.HostBinToolVariable("syspropCmd", "sysprop_cpp")
 }

cc/makevars.go

@@ -148,6 +148,8 @@ func makeVarsProvider(ctx android.MakeVarsContext) {
 	ctx.Strict("AIDL_CPP", "${aidlCmd}")
 	ctx.Strict("ALLOWED_MANUAL_INTERFACE_PATHS", strings.Join(allowedManualInterfacePaths, " "))
 
+	ctx.Strict("M4", "${m4Cmd}")
+
 	ctx.Strict("RS_GLOBAL_INCLUDES", "${config.RsGlobalIncludes}")
 
 	ctx.Strict("SOONG_STRIP_PATH", "${stripPath}")