Merge r340931, r340932 into the 7.0 branch: [mips] [mips] Fix microMIPS unconditional branch offset handling

[atanasyan]

Bugzilla Link	39609
Resolution	FIXED
Resolved on	Nov 12, 2018 21:19
Version	trunk
OS	All
Blocks	#38454
CC	@tstellar
Fixed by commit(s)	r340931 r340932 r346735 r346736

Extended Description

Please merge the following revisions to the 7.0 branch. The fix was intended for release in 7.0 but missed the deadline.

https://reviews.llvm.org/rL340931
https://reviews.llvm.org/rL340932

[tstellar]

Merged: r346735 r346736