Bump GCC requirements to 4.8. Close #1442

cmake/TestCXX11.cmake

@@ -34,6 +34,6 @@ if(NOT DEFINED cxx11check)
 			"Error in C++11 check:\n${_CXX11Check_tryout}\n")
 		message(STATUS "Checking for C++11 support - not supported")
 		message(FATAL_ERROR " Upgrade your compiler.\n"
-			" GCC 4.7+ and Clang 3.2+ are known to work.")
+			" GCC 4.8+ and Clang 3.2+ are known to work.")
 	endif()
 endif()

cmake/cxx11check/main.cpp

@@ -10,6 +10,7 @@
 // and this notice are preserved. This file is offered as-is, without any
 // warranty.
 
+#include <map>
 
 template <typename T>
 struct check {
@@ -55,4 +56,8 @@ void test();
 void test() { func<foo>(0); }
 }
 
-int main() { return 0; }
+int main() {
+    std::map<int, int> m;
+    m.emplace(2, 4);
+    return 0;
+}