patch 8.2.2833: two key command cancelled by moving mouse when using popup

Problem:    Two key command cancelled by moving mouse when using popup.
            (Sergey Vlasov)
Solution:   Ignore K_MOUSEMOVE in plain_vgetc().
diff --git a/src/getchar.c b/src/getchar.c
index cf2711b..185b73b 100644
--- a/src/getchar.c
+++ b/src/getchar.c
@@ -1932,7 +1932,9 @@
 
     do
 	c = safe_vgetc();
-    while (c == K_IGNORE || c == K_VER_SCROLLBAR || c == K_HOR_SCROLLBAR);
+    while (c == K_IGNORE
+	    || c == K_VER_SCROLLBAR || c == K_HOR_SCROLLBAR
+	    || c == K_MOUSEMOVE);
 
     if (c == K_PS)
 	// Only handle the first pasted character.  Drop the rest, since we