[libcxx] Add "flag" default arg: basic_regex ptr_size_flag ctor
Summary:
The synopsis in C++11 subclause 28.8 [re.regex] has:
```
basic_regex(const charT* p, size_t len,
flag_type f = regex_constants::ECMAScript);
```
The default argument is added to libc++ by this change.
Reviewers: mclow.lists, rsmith, hubert.reinterpretcast
Subscribers: cfe-commits
Differential Revision: https://reviews.llvm.org/D22702
Reapplies r277966.
Patch by Jason Liu!
git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@277968 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed