Attempt to fix test failure for armv8.
Attempt to fix test failure for armv8.

Looks like armv8 can't handle a thousand threads, which GWP-ASan
requests when running a synchronised mutex test. Limiting this to 100 to
attempt to fix the build issue.

git-svn-id: c199f293c43da69278bea8e88f92242bf3aa95f7@362163 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt,llvm-mirror/compiler-rt