AAPT: ProGuard config for components in main dex.

Create an analogue of "aapt -G" which outputs a proguard configuration
that keeps only components which need to be in the main dex.

BUG: 27383099

Change-Id: Ic18c8c563794ff27a5598a214111d1b446a005f1
diff --git a/tools/aapt/Main.h b/tools/aapt/Main.h
index e84c4c5..a493842 100644
--- a/tools/aapt/Main.h
+++ b/tools/aapt/Main.h
@@ -54,6 +54,7 @@
         bool includePrivate, bool emitCallback);
 
 extern android::status_t writeProguardFile(Bundle* bundle, const sp<AaptAssets>& assets);
+extern android::status_t writeMainDexProguardFile(Bundle* bundle, const sp<AaptAssets>& assets);
 
 extern bool isValidResourceType(const String8& type);