PR18513: make gcc compatible layout for bit-fields with explicit aligned...

PR18513: make gcc compatible layout for bit-fields with explicit aligned attribute, by Dmitry Polukhin
Fix binary compatibility issue with GCC.
Differential Revision: http://reviews.llvm.org/D14980


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@257462 91177308-0d34-0410-b5e6-96231b3b80d8