Clear up some object lifetime issues for ASTContext and Preprocessor.

Bug: 18343568
https://code.google.com/p/android/issues/detail?id=79142

llvm-rs-cc was accidentally freeing memory that was still in use. The
ASTContext and Preprocessor contain several strings and other pieces
of data that are used during the generation of our reflected code.

(cherry picked from commit c546630bbcc631bc963609c2288d4d9a18753e8d)

Change-Id: I900faa3beb6b1e21524708ca2a23468da1de6011
1 file changed