core: fix a typo in the Win32 timer code.

src/timer.cpp

@@ -110,7 +110,7 @@ private:
 #elif defined _WIN32
         LARGE_INTEGER tmp;
         QueryPerformanceFrequency(&tmp);
-        return = 1e3f / tmp.QuadPart;
+        return 1e3f / tmp.QuadPart;
 #elif defined __CELLOS_LV2__
         return 1e3f / sys_time_get_timebase_frequency();
 #else