Repackage annotation compiler dependencies using jarjar directly

[TWiStErRob]

Description

Add two more steps to build:

• repackage (change and fatjar packages)
• ProGuard shrink (remove unused classes)

Sizes of compiler-4.2.0-SNAPSHOT.jar:

Name	Size	Comment
Original	72,239	raw classes from this module
Repackaged	2,648,476	(incl. Guava, Javapoet, Auto)
Proguarded	251,481	dontobfuscate,dontoptimize,shrink; keep all module code

The only drawback I see is the inclusion of jarjar JAR in the libs folder, only 1.3 is published on Maven Central.

Motivation and Context

Fixes #2059

[TWiStErRob]

Warning: I didn't test-run this change, only that the .jar file is built correctly and similar to the original.

[sjudd]

Thanks @TWiStErRob, working on testing this.

[sjudd]

For posterity, #2363 lets us use a gradle plugin, but requires modifying Glide's source to accomplish the same thing.

[sjudd]

I patched your cl and uploaded it (with the changes I've indicated here) to sonatypes SNAPSHOT. Then I created a sample app and added a dependency on the new snapshot. It's a little hard to tell because AS seems to ignore the various gradle cache configurations, but at least from the command line I was able to verify that the findbugs conflict mentioned in the attached issue is fixed after this change, the app builds successfully, and the expected Glide classes are generated.

Probably ok to merge this.

[sjudd]

Remove the two testCompile lines (they're totally unused anyway).

[sjudd]

compileOnly here is fine since these are just annotations anyway. Doing so will resolve the findbugs conflict as well as those with javapoet and auto-service.

[sjudd]

@TWiStErRob let me know if you want me to take this over, thank you for putting this up. Great idea! I really appreciate the help.

[sjudd]

Merged here: a0e388e. Thanks!