Fix leaked file descriptor with ENTROPY_STATS

cppcheck found a leaked file descriptor in the debugging code
enabled by defining ENTROPY_STATS. Fixes issue #60.

Change-Id: I0c1d0669cb94d44fed77860f97b82763be06b7cb

vp8/encoder/onyx_if.c

@@ -2529,6 +2529,7 @@ void vp8_remove_compressor(VP8_PTR *ptr)
             }
 
             fprintf(fmode, "};\n");
+            fclose(fmode);
         }
 #endif