sendf: Fix whitespace in infof/failf concatenation

Strings broken on multiple rows in the .c file need to have appropriate
whitespace padding on either side of the concatenation point to render
a correct amalgamated string. Fix by adding a space at the occurrences
found.

Closes #2986
Reviewed-by: Daniel Stenberg <daniel@haxx.se>

lib/security.c

@@ -422,7 +422,7 @@ static int sec_set_protection_level(struct connectdata *conn)
 
   if(!conn->sec_complete) {
     infof(conn->data, "Trying to change the protection level after the"
-                      "completion of the data exchange.\n");
+                      " completion of the data exchange.\n");
     return -1;
   }