Simplify expression in makeline()

This expression was wrong, but it was causing a false positive
in some compilers that couldn't see that error() cannot return.
The actual problem of the line is that it was too complex and it is better
to split it in simplex expressions.

ed.c

@@ -192,8 +192,10 @@ makeline(char *s, int *off)
 	char c, *begin = s;
 
 	if (lastidx >= idxsize) {
-		if (idxsize > SIZE_MAX - NUMLINES ||
-		    !(lp = realloc(zero, (idxsize + NUMLINES) * sizeof(*lp))))
+		lp = NULL;
+		if (idxsize <= SIZE_MAX - NUMLINES)
+		    lp = realloc(zero, (idxsize + NUMLINES) * sizeof(*lp));
+		if (!lp)
 			error("out of memory");
 		idxsize += NUMLINES;
 		zero = lp;