[PDB] Make variables.test to pass using a 32-bit compiler too
variables.test depends on mangled names, but the mangling depends
on the bitness. This patch specifies the bitness explicitly, so mangled names
doesn't differ when a 32-bit version of the compiler is used.
Reviewers: stella.stamenova, asmith
Reviewed By: stella.stamenova
Differential Revision: https://reviews.llvm.org/D51158