Set CMAKE_CXX_STANDARD if we seem to need to set it. :/

Change-Id: I550ff1b4542bf9fc34cfe50e7fa4ac8fb55cc804
Reviewed-on: https://code-review.googlesource.com/c/re2/+/59910
Reviewed-by: Perry Lorier <perryl@google.com>
Reviewed-by: Paul Wankadia <junyer@google.com>
1 file changed