Fixed bug #176

[I'm fixing this for the public headers, but I'm not going to bother for the SDL library code (yet)]

To clarify: Normaly, GCC (or, to be precise, the preprocessor) will ignore
this, and compile the code happily. However, one can specify -Wundef to get a
warning about this.

One can probably argue whether to consider this a bug or not; but I think that
(a) from a semantic point of view, using "#if FOO" when FOO is not defined is
strange, and (b) since it is possible to trigger a warning about this, and a
trivial fix exists, it should be corrected.

I can think of two alternative patches, BTW:
1) Simply use #define HAVE_FOO 0, instead of not defining HAVE_FOO at all
2) Change
  #if HAVE_FOO
to
  #if HAVE_FOO+0
which always does the right thing.

But I think I still prefer the attached patch :-).

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%401633

include/SDL_config_win32.h

@@ -63,7 +63,7 @@ typedef unsigned int uintptr_t;
 
 /* Enabled for SDL 1.2 (binary compatibility) */
 #define HAVE_LIBC	1
-#if HAVE_LIBC
+#ifdef HAVE_LIBC
 /* Useful headers */
 #define HAVE_STDIO_H 1
 #define STDC_HEADERS 1

include/SDL_syswm.h

@@ -46,7 +46,7 @@ typedef struct SDL_SysWMinfo SDL_SysWMinfo;
 #else
 
 /* This is the structure for custom window manager events */
-#if SDL_VIDEO_DRIVER_X11
+#if defined(SDL_VIDEO_DRIVER_X11)
 #if defined(__APPLE__) && defined(__MACH__)
 /* conflicts with Quickdraw.h */
 #define Cursor X11Cursor
@@ -100,7 +100,7 @@ typedef struct SDL_SysWMinfo {
 	} info;
 } SDL_SysWMinfo;
 
-#elif SDL_VIDEO_DRIVER_NANOX
+#elif defined(SDL_VIDEO_DRIVER_NANOX)
 #include <microwin/nano-X.h>
 
 /* The generic custom event structure */
@@ -115,7 +115,7 @@ typedef struct SDL_SysWMinfo {
 	GR_WINDOW_ID window ;	/* The display window */
 } SDL_SysWMinfo;
 
-#elif SDL_VIDEO_DRIVER_WINDIB || SDL_VIDEO_DRIVER_DDRAW
+#elif defined(SDL_VIDEO_DRIVER_WINDIB) || defined(SDL_VIDEO_DRIVER_DDRAW)
 #define WIN32_LEAN_AND_MEAN
 #include <windows.h>
 
@@ -135,7 +135,7 @@ typedef struct SDL_SysWMinfo {
 	HGLRC hglrc;			/* The OpenGL context, if any */
 } SDL_SysWMinfo;
 
-#elif SDL_VIDEO_DRIVER_RISCOS
+#elif defined(SDL_VIDEO_DRIVER_RISCOS)
 
 /* RISC OS custom event structure */
 struct SDL_SysWMmsg {
@@ -152,7 +152,7 @@ typedef struct SDL_SysWMinfo {
 	int window;		/* The RISC OS display window */
 } SDL_SysWMinfo;
 
-#elif SDL_VIDEO_DRIVER_PHOTON
+#elif defined(SDL_VIDEO_DRIVER_PHOTON)
 #include <sys/neutrino.h>
 #include <Ph.h>