[ADD][VIM] C header guard snippet

vim/.vim/UltiSnips/c.snippets

@@ -0,0 +1,14 @@
+snippet once "Include header once only guard"
+#ifndef ${1:`!p
+if not snip.c:
+	import random, string
+	name = re.sub(r'[^A-Za-z0-9]+','_', snip.fn).upper()
+	snip.rv = name.upper()
+else:
+    snip.rv = snip.c`}
+# define $1
+
+${0}
+
+#endif /* !$1 */
+endsnippet