Don't execute an empty command for an empty branch in an /IF.

Old behaviour was that /if (0) { echo y } would execute an empty command for the missing else
case, which winds up doing send_text("").


git-svn-id: svn://svn.code.sf.net/p/bitchx/code/trunk@513 13b04d17-f746-0410-82c6-800466cd88b0

source/if.c

@@ -157,7 +157,7 @@ BUILT_IN_COMMAND(ifcmd)
 				current_line = NULL;
 		}
 
-		if (current_line)
+		if (current_line && *current_line)
 			parse_line(NULL, current_line, subargs, 0, 0, 1);
 
 		break;