add support to build with MSVC /Gr (fastcall mode for x86)

not enabled by default nor exposed at the moment

src/util/scoped_ctrl_c.h

@@ -20,16 +20,17 @@ Revision History:
 #define SCOPED_CTRL_C_H_
 
 #include"event_handler.h"
+#include"util.h"
 
 struct scoped_ctrl_c {
     event_handler & m_cancel_eh;
     bool m_first;
     bool m_once;
     bool m_enabled;
-   void (*m_old_handler)(int);
+    void  (STD_CALL *m_old_handler)(int);
     scoped_ctrl_c * m_old_scoped_ctrl_c;
     static scoped_ctrl_c * g_obj;
-    static void on_ctrl_c(int);
+    static void STD_CALL on_ctrl_c(int);
 public:
     // If once == true, then the cancel_eh is invoked only at the first Ctrl-C.
     // The next time, the old signal handler will take over.

src/util/util.h

@@ -69,6 +69,12 @@ COMPILE_TIME_ASSERT(sizeof(int64) == 8);
 #define THREAD_LOCAL 
 #endif
 
+#ifdef _MSC_VER
+# define STD_CALL __cdecl
+#else
+# define STD_CALL
+#endif
+
 #ifdef __fallthrough
 # define Z3_fallthrough __fallthrough
 #elif defined(__has_cpp_attribute)

src/util/warning.cpp

@@ -28,7 +28,7 @@ Revision History:
 #define PRF sprintf_s
 #define VPRF vsprintf_s
 
-void myInvalidParameterHandler(
+void STD_CALL myInvalidParameterHandler(
     const wchar_t* expression,
     const wchar_t* function, 
     const wchar_t* file,