patch 9.0.0828: various typos

Problem:    Various typos.
Solution:   Correct typos. (closes #11432)
diff --git a/src/os_win32.c b/src/os_win32.c
index ca1799f..fc6ea5e 100644
--- a/src/os_win32.c
+++ b/src/os_win32.c
@@ -1307,7 +1307,7 @@
     else
 	direction = zDelta >= 0 ? KE_MOUSEDOWN : KE_MOUSEUP;
 
-    // Decode the win32 console key modifers into Vim mouse modifers.
+    // Decode the win32 console key modifiers into Vim mouse modifiers.
     if (pmer->dwControlKeyState & SHIFT_PRESSED)
 	modifiers |= MOD_MASK_SHIFT; // MOUSE_SHIFT;
     if (pmer->dwControlKeyState & (RIGHT_CTRL_PRESSED | LEFT_CTRL_PRESSED))