[msan] Prevent initialization failure with newer (2.23+) glibc in use.

This patch is pretty the same as http://reviews.llvm.org/D20235 that we used
for ASan. Using the same hack for MSan fixes its initialization with newer
Glibc in use.

Differential Revision: https://reviews.llvm.org/D24736

llvm-svn: 282232