Add check in configure to ensure c++ compiler

configure.in

@@ -4,6 +4,8 @@
 AC_INIT(rAthena)
 AC_REVISION($Revision$)
 AC_PREREQ([2.59])
+AC_LANG([C++])
+AC_LANG_COMPILER_REQUIRE
 AC_CONFIG_SRCDIR([src/common/cbasetypes.h])
 AC_CONFIG_FILES([Makefile src/common/Makefile])
 AC_CONFIG_FILES([3rdparty/mt19937ar/Makefile 3rdparty/libconfig/Makefile 3rdparty/yaml-cpp/Makefile])
@@ -437,7 +439,6 @@ AC_PROG_CXX
 AC_PATH_PROG(AR, ar)
 AC_LANG([C++])
 
-
 CFLAGS="$CFLAGS -pipe -ffast-math -Wall"
 CPPFLAGS="$CPPFLAGS -I../common"
 CXXFLAGS="$CXXFLAGS -std=c++11"