Fixes rgb32to16 conversion for I think all platforms since the int8

cast should never have worked. Tested on PowerPC and fixes the black GUI
to show the content.
patch by Rene Rebe <rene at exactcode dot de>

Originally committed as revision 14983 to svn://svn.mplayerhq.hu/mplayer/trunk/postproc

postproc/rgb2rgb_template.c

@@ -403,10 +403,8 @@ static inline void RENAME(rgb32to16)(const uint8_t *src, uint8_t *dst, unsigned
 #endif
 	while(s < end)
 	{
-		// FIXME on bigendian
-		const int src= *s; s += 4;
-		*d++ = ((src&0xFF)>>3) + ((src&0xFC00)>>5) + ((src&0xF80000)>>8);
-//		*d++ = ((src>>3)&0x1F) + ((src>>5)&0x7E0) + ((src>>8)&0xF800);
+		register int rgb = *(uint32_t*)s; s += 4;
+		*d++ = ((rgb&0xFF)>>3) + ((rgb&0xFC00)>>5) + ((rgb&0xF80000)>>8);
 	}
 }