Rename OSMO_AUTH_ALG_XOR to OSMO_AUTH_ALG_XOR_3G

Let's disambiguate.  Our existing OSMO_AUTH_ALG_XOR was always only
the XOR-3G algorithm.  Now that we recently introduced XOR-2G,
let's rename (with backwards compatibility #define).

Change-Id: I446e54d0ddf4a18c46ee022b1249af73552e3ce1
diff --git a/src/gsm/auth_core.c b/src/gsm/auth_core.c
index af03ace..ce6ba7d 100644
--- a/src/gsm/auth_core.c
+++ b/src/gsm/auth_core.c
@@ -208,7 +208,7 @@
 	{ OSMO_AUTH_ALG_COMP128v1, "COMP128v1" },
 	{ OSMO_AUTH_ALG_COMP128v2, "COMP128v2" },
 	{ OSMO_AUTH_ALG_COMP128v3, "COMP128v3" },
-	{ OSMO_AUTH_ALG_XOR, "XOR" },
+	{ OSMO_AUTH_ALG_XOR_3G, "XOR-3G" },
 	{ OSMO_AUTH_ALG_MILENAGE, "MILENAGE" },
 	{ OSMO_AUTH_ALG_XOR_2G, "XOR-2G" },
 	{ 0, NULL }