[llvm-lipo] Implement -create (with hardcoded alignments)

Creates universal binary output file from input files. Currently uses
hard coded value for alignment.  Want to get the create functionality
approved before implementing the alignment function.

Patch by Anusha Basana <anusha.basana@gmail.com>

Differential Revision: https://reviews.llvm.org/D64102

llvm-svn: 366142