Move "extern C" to ppscale header

src/gui/sdlmain.cpp

@@ -57,9 +57,7 @@
 #include "control.h"
 #include "render.h"
 
-extern "C" {
 #include "../libs/ppscale/ppscale.h"
-}
 
 #define MAPPERFILE "mapper-sdl2-" VERSION ".map"
 //#define DISABLE_JOYSTICK

src/libs/ppscale/ppscale.h

@@ -9,6 +9,10 @@
 #ifndef PPSCALE_H
 #define PPSCALE_H
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 int pp_getscale /* calculate integer scales for pixel-perfect magnification */
 (	int    win,  int hin,  /* input dimensions                  */
 	double par,            /* input pixel aspect ratio          */
@@ -30,4 +34,8 @@ int pp_scale /* magnify an image in a pixel-perfect manner */
 	int   sx,   int sy      /* horisontal and vertical scales   */
 ); /* return -1 on error and 0 on success */
 
+#ifdef __cplusplus
+}
+#endif
+
 #endif /* PPSCALE_H */