Fix the MinGW builder. Apparently std::call_once and
authorZachary Turner <zturner@google.com>
Sat, 21 Jun 2014 00:24:51 +0000 (00:24 +0000)
committerZachary Turner <zturner@google.com>
Sat, 21 Jun 2014 00:24:51 +0000 (00:24 +0000)
commitd119fa028ac28ed4ec0bf11d1178bf58dedf72a7
treef1599951a19fb314bdc0a677d4934051daeaf0e7
parentb4076b290eff353ab72a7fc2e10b45b757b051e7
Fix the MinGW builder.  Apparently std::call_once and
std::recursive_mutex are not available on MinGW and breaks the
builder.  Revert to using a function local static and sys::Mutex
just to get the tree green until we figure out a better solution.

llvm-svn: 211424
llvm/lib/Support/ManagedStatic.cpp