[ADT] Use explicit constructors for DenseMapPair to work around compiler issues.

Inheriting constructors from std::pair caused clang-3.8 to treat some DenseMap
initializer_list constructor calls as ambiguous, which broke several bots. This
commit explicitly defines DenseMapPair's constructos to work around the issue.

https://reviews.llvm.org/D53726

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@345411 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed