Add dSYM folder to C.gitignore for OSX env

See https://github.com/github/gitignore/pull/527

> For C.gitignore add dSYM folder from Mac OS X to gitignore

C.gitignore

@@ -27,3 +27,6 @@
 *.i*86
 *.x86_64
 *.hex
+
+# Debug files
+*.dSYM/