patch 9.0.0342: ":wincmd =" equalizes in two directions

Problem:    ":wincmd =" equalizes in two directions.
Solution:   Make ":vertical wincmd =" equalize vertically only and
            ":horizontal wincmd =" equalize horizontally only.
diff --git a/src/window.c b/src/window.c
index 65dec10..3632735 100644
--- a/src/window.c
+++ b/src/window.c
@@ -434,12 +434,16 @@
 			| ((nchar == 'H' || nchar == 'K') ? WSP_TOP : WSP_BOT));
 		break;
 
-// make all windows the same height
+// make all windows the same width and/or height
     case '=':
+		{
+		    int mod = cmdmod.cmod_split & (WSP_VERT | WSP_HOR);
 #ifdef FEAT_GUI
-		need_mouse_correct = TRUE;
+		    need_mouse_correct = TRUE;
 #endif
-		win_equal(NULL, FALSE, 'b');
+		    win_equal(NULL, FALSE,
+			   mod == WSP_VERT ? 'v' : mod == WSP_HOR ? 'h' : 'b');
+		}
 		break;
 
 // increase current window height