Remove guards for SWIG.

Given that various other things in `re2.h` never had guards for SWIG
and that nobody ever complained, we can save ourselves some cruft...

Change-Id: I0d6aa66577d4c16c4e1ed60696a6f2144756dffe
Reviewed-on: https://code-review.googlesource.com/c/re2/+/60310
Reviewed-by: Paul Wankadia <junyer@google.com>
Reviewed-by: Julien Goodwin <julieng@google.com>
1 file changed