Avoid possible buffer overflow.

clang-tidy rightly complains that this code for concatenating two strings
is incorrect because it doesn't take into account the space used by the
first string when appending the second string. Just use snprintf instead.

Bug: N/A
Test: builds, boots
Change-Id: Ifdaff43a87301a876369635013516aab41cd48c3
diff --git a/rild/rild.c b/rild/rild.c
index dbd925d..685ef70 100644
--- a/rild/rild.c
+++ b/rild/rild.c
@@ -144,8 +144,8 @@
         exit(0);
     }
     if (strncmp(clientId, "0", MAX_CLIENT_ID_LENGTH)) {
-        strncpy(ril_service_name, ril_service_name_base, MAX_SERVICE_NAME_LENGTH);
-        strncat(ril_service_name, clientId, MAX_SERVICE_NAME_LENGTH);
+        snprintf(ril_service_name, sizeof(ril_service_name), "%s%s", ril_service_name_base,
+                 clientId);
     }
 
     if (rilLibPath == NULL) {