SDLvncviewer: fix translation of the Tab key

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

TODO

@@ -4,7 +4,6 @@ immediate:
 Implement ZYWRLE decoding in libvncclient
 make SDLvncviewer more versatile (test for missing keys, introduce scrollbars,
 	make scrollable with 2xCtrl and mouse drag)
-	- Tab does not work
 	- Left Ctrl + A does not work
 	- 2nd and 3rd mouse button are switched
 Clean up ZRLE (probably not thread-safe: zrleBeforeBuf, zrlePaletteHelper)

client_examples/SDLvncviewer.c

@@ -58,7 +58,7 @@ static rfbKeySym SDL_key2rfbKeySym(SDL_KeyboardEvent* e) {
 	rfbKeySym k = 0;
 	switch(e->keysym.sym) {
 	case SDLK_BACKSPACE: k = XK_BackSpace; break;
-	case SDLK_TAB: k = XK_ISO_Left_Tab; break;
+	case SDLK_TAB: k = XK_Tab; break;
 	case SDLK_CLEAR: k = XK_Clear; break;
 	case SDLK_RETURN: k = XK_Return; break;
 	case SDLK_PAUSE: k = XK_Pause; break;