re2: use the same C++ std used by abseil-cpp (#43288)

Co-authored-by: jmcarcell <jmcarcell@users.noreply.github.com>

var/spack/repos/builtin/packages/re2/package.py

@@ -40,5 +40,6 @@ def cmake_args(self):
         args = [
             self.define_from_variant("BUILD_SHARED_LIBS", "shared"),
             self.define_from_variant("CMAKE_POSITION_INDEPENDENT_CODE", "pic"),
+            f"-DCMAKE_CXX_STANDARD={self.spec['abseil-cpp'].variants['cxxstd'].value}",
         ]
         return args