cc3200/appsign.sh: Use md5 if running under Darwin.

cc3200/appsign.sh

@@ -9,7 +9,12 @@ fi
 BUILD=$1
 
 # Generate the MD5 hash
+# md5 on Darwin, md5sum on Unix
+if [ `uname -s` = "Darwin" ]; then
+echo -n `md5 -q $BUILD/application.bin` > __md5hash.bin
+else
 echo -n `md5sum --binary $BUILD/application.bin | awk '{ print $1 }'` > __md5hash.bin
+fi
 
 # Concatenate it with the application binary
 cat $BUILD/application.bin __md5hash.bin > $BUILD/mcuimg.bin