[asan] Fix printing of long reports to logcat on Android.

__android_log_write has an implicit message length limit.
Print one line at a time.
Add two helpers to IRBuilder to flesh the interface out to N-width
integers. Complements the interfaces it is wrapping.
[SROA] Use the correct index integer size in GEPs through non-default
address spaces.

This isn't really a correctness issue (the values are truncated) but its
much cleaner.

Patch by Matt Arsenault!
[mips] Treat -mcpu=generic the same way as an empty CPU string.

Summary:
This should fix the MCJIT unit tests that were broken by r201792 on the MIPS buildbot.
MIPS currently uses the default implementation of sys::getHostCPUName() which
always returns "generic". For now, we will accept "generic" and coerce it to
"mips32" or "mips64" depending on the target architecture like we do for empty
CPU names.

Reviewers: jacksprat, matheusalmeida

Reviewed By: jacksprat

Differential Revision: http://llvm-reviews.chandlerc.com/D2878
Fix typo
Add a StmtPrinter test for implicit and explicit conversion operator calls.

Put back a comment that I removed too aggressively.