Add aidl file support to java builds

Add support for aidl files listed in srcs for java builds, and
an aidl_preprocess module type for framework and sdk aidls.

Change-Id: I3aa537f4483822e5b534c74d0b35f13a938f8947
diff --git a/Blueprints b/Blueprints
index 84c9913..2acc065 100644
--- a/Blueprints
+++ b/Blueprints
@@ -86,6 +86,7 @@
         "common/glob.go",
         "common/module.go",
         "common/paths.go",
+        "common/util.go",
     ],
 }
 
@@ -143,6 +144,7 @@
     ],
     srcs: [
         "java/builder.go",
+        "java/gen.go",
         "java/java.go",
         "java/resources.go",
     ],