generateDrawablesFromArt is fixed on wondows.

app/build.gradle

@@ -37,7 +37,10 @@ preBuild.dependsOn createVersionXML
 //
 task generateDrawablesFromArt {
 	doLast {
-		def buildDir = (new File(project.buildDir,'art')).toString()
+        String backslash= System.getProperty("file.separator")
+        def buildDir = (new File(project.buildDir,'art')).toString()
+        buildDir = buildDir.replace(backslash,"/")
+        println 'make -C app/src/main/art RES=../res TMP='+buildDir
         def p = ('make -C app/src/main/art RES=../res TMP='+buildDir).execute()
 		p.consumeProcessOutput()
 		p.waitFor()