tresize: move for loop outside if

There is no need to check that slide > 0 before executing loop.
If slide <= 0, loop stops immediately.

st.c

@@ -2780,17 +2780,16 @@ tresize(int col, int row) {
 	}
 
 	/* free unneeded rows */
-	i = 0;
+	for(i = 0; i < slide; i++) {
+		free(term.line[i]);
+		free(term.alt[i]);
+	}
 	if(slide > 0) {
 		/*
 		 * slide screen to keep cursor where we expect it -
 		 * tscrollup would work here, but we can optimize to
 		 * memmove because we're freeing the earlier lines
 		 */
-		for(/* i = 0 */; i < slide; i++) {
-			free(term.line[i]);
-			free(term.alt[i]);
-		}
 		memmove(term.line, term.line + slide, row * sizeof(Line));
 		memmove(term.alt, term.alt + slide, row * sizeof(Line));
 	}