patch 8.2.1856: "2resize" uses size of current window

Problem:    "2resize" uses size of current window.
Solution:   Use size of resized window. (Yasuhiro Matsumoto, closes #7152)
diff --git a/src/ex_docmd.c b/src/ex_docmd.c
index 66c0b66..1ccd38e 100644
--- a/src/ex_docmd.c
+++ b/src/ex_docmd.c
@@ -6365,7 +6365,7 @@
     if (cmdmod.split & WSP_VERT)
     {
 	if (*eap->arg == '-' || *eap->arg == '+')
-	    n += curwin->w_width;
+	    n += wp->w_width;
 	else if (n == 0 && eap->arg[0] == NUL)	// default is very wide
 	    n = 9999;
 	win_setwidth_win((int)n, wp);
@@ -6373,7 +6373,7 @@
     else
     {
 	if (*eap->arg == '-' || *eap->arg == '+')
-	    n += curwin->w_height;
+	    n += wp->w_height;
 	else if (n == 0 && eap->arg[0] == NUL)	// default is very high
 	    n = 9999;
 	win_setheight_win((int)n, wp);