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/Command.cpp b/tools/aapt/Command.cpp
index db40416..9976d00 100644
--- a/tools/aapt/Command.cpp
+++ b/tools/aapt/Command.cpp
@@ -2631,6 +2631,12 @@
         goto bail;
     }
 
+    // Write out the Main Dex ProGuard file
+    err = writeMainDexProguardFile(bundle, assets);
+    if (err < 0) {
+        goto bail;
+    }
+
     // Write the apk
     if (outputAPKFile) {
         // Gather all resources and add them to the APK Builder. The builder will then