[LLVM/Support] - Create no-arguments constructor for llvm::Regex

This is useful when need to defer the construction,
e.g. using Regex as a member of class.

Differential revision: https://reviews.llvm.org/D24101

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@280339 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed