cmake HAVE_CXX11_EMPLACE examples

tmikov/jscomp runtime/CMakeLists.txt :13

CHECK_CXX_SOURCE_COMPILES("
#include <map>
int main (int, char **) {
  std::map<int,int> m;
  m.emplace(1,2);
  return 0;
}
" HAVE_CXX11_EMPLACE
)