Add missing CONFIG_DAALA_EC declaration.

Without first including ./aom_config.h in aom_dsp/prob.c the memmove
 function is implicitly defined and causes a compiler warning.

Change-Id: I339d0389f10324a1085aba7d6492b2159a14da92

aom_dsp/prob.c

@@ -9,6 +9,8 @@
  * PATENTS file, you can obtain it at www.aomedia.org/license/patent.
  */
 
+#include "./aom_config.h"
+
 #if CONFIG_DAALA_EC
 #include <string.h>
 #endif