test: tiny_ssim: Don't include config.h

tiny_ssim is built for the build host, not for the target platform.
Therefore, it mustn't include the config.h header, which is set up
specifically for the target platform and compiler.

This fixes cross building for older WinStore platforms, where
config.h contains "#define getenv(x) NULL".

Signed-off-by: Martin Storsjö <martin@martin.st>

tests/tiny_ssim.c

@@ -27,7 +27,6 @@
  * overlapped 8x8 block sums, rather than the original gaussian weights.
  */
 
-#include "config.h"
 #include <inttypes.h>
 #include <limits.h>
 #include <math.h>