Revert minidump changes

This reverts the following two commits:

Revert "Extend r356573 (minidump UUID handling) to cover elf build-ids too"
Revert "Fix UUID decoding from minidump files"

Greg's original commit broke the sanitizer bot which has been red for
several days now.

http://green.lab.llvm.org/green/view/LLDB/job/lldb-sanitized/

llvm-svn: 356806