[sofia-sip] fix build on newer clang

libs/sofia-sip/.update

@@ -1 +1 @@
-Sat Mar 28 10:36:01 UTC 2020
+Wed Apr  1 12:53:24 MDT 2020

libs/sofia-sip/libsofia-sip-ua/sip/sip_pref_util.c

@@ -312,7 +312,7 @@ int sip_prefs_matching(char const *pvalue,
 int sip_is_callerpref(char const *param)
 {
 #define MATCH(s) \
-  (su_casenmatch(param + 1, s + 1, strlen(s) - 1) && \
+  (su_casenmatch(&param[1], &s[1], strlen(s) - 1) && \
    (param[strlen(s)] == '=' || param[strlen(s)] == '\0'))
 
   int xor = 0, base = 0;