Log Message:
Add following line
  CPPFLAGS+=     -std=c++11
to fix (at least) pkgsrc NetBSD 7.0.1_PATCH/x86_64 2016-10-13 12:53 build

Just for FYI, without FLAGS,
| checking re2/re2.h usability... no
| checking re2/re2.h presence... no
| checking for re2/re2.h... no
| configure: error: test for RE2 header failed

with CXXFLAGS+=, getting below
| configure: WARNING: re2/re2.h: accepted by the compiler, rejected by the \ 
preprocessor!
| configure: WARNING: re2/re2.h: proceeding with the compiler's result
Thanks joerg@,