Add workaround for Sema issue found in <rdar://problem/9188004>, which leads...

Add workaround for Sema issue found in <rdar://problem/9188004>, which leads to an assertion failure in the uninitialized variables analysis.  The problem is that Sema isn't properly registering a variable in a DeclContext (which -Wuninitialized relies on), but
my expertise on the template instantiation logic isn't good enough to fix this problem for real.  This patch worksaround the
problem in -Wuninitialized, but we should fix it for real later.

llvm-svn: 128443