[CLEANUP] hash: move the avalanche hash code globally available

We'll use this hash at other places, let's make it globally available.
The function has also been renamed because its "chash_hash" name was
not appropriate.
diff --git a/src/standard.c b/src/standard.c
index 60f5af1..1ab2194 100644
--- a/src/standard.c
+++ b/src/standard.c
@@ -1106,6 +1106,12 @@
 	return ret;
 }
 
+/* hash a 32-bit integer to another 32-bit integer */
+unsigned int full_hash(unsigned int a)
+{
+	return __full_hash(a);
+}
+
 /*
  * Local variables:
  *  c-indent-level: 8