Add dependency generation to Aapt for R.java

Make Aapt generate a dependency file in the location specified
by RClassDir for R.java if the --generate-dependencies flag is set.
This dependency file is then read by the ant exec loop task
to see whether to recreate R.java.

Change-Id: I7152dac86b6ea0e448ef65e3a95694afe233c789
diff --git a/tools/aapt/Main.cpp b/tools/aapt/Main.cpp
index 732541d..8edb5b5 100644
--- a/tools/aapt/Main.cpp
+++ b/tools/aapt/Main.cpp
@@ -146,7 +146,9 @@
         "   --custom-package\n"
         "       generates R.java into a different package.\n"
         "   --extra-packages\n"
-        "       generate R.java for libraries. Separate libraries with ';'.\n"
+        "       generate R.java for libraries. Separate libraries with ':'.\n"
+        "   --generate-dependencies\n"
+        "       generate a dependency file for R.java.\n"
         "   --auto-add-overlay\n"
         "       Automatically add resources that are only in overlays.\n"
         "   --rename-manifest-package\n"
@@ -486,6 +488,8 @@
                         goto bail;
                     }
                     bundle.setExtraPackages(argv[0]);
+                } else if (strcmp(cp, "-generate-dependencies") == 0) {
+                    bundle.setGenDependencies(true);
                 } else if (strcmp(cp, "-utf16") == 0) {
                     bundle.setWantUTF16(true);
                 } else if (strcmp(cp, "-rename-manifest-package") == 0) {