Moved some more 16-bit functions to user16.c.
A few fixes for -DSTRICT.

diff --git a/windows/class.c b/windows/class.c
index b6a7b64..009cf6f 100644
--- a/windows/class.c
+++ b/windows/class.c
@@ -1011,7 +1011,7 @@
         break;
     case GCL_HBRBACKGROUND:
         retval = (LONG)class->hbrBackground;
-        class->hbrBackground = newval;
+        class->hbrBackground = (HBRUSH)newval;
         break;
     case GCL_HCURSOR:
         retval = (LONG)class->hCursor;
@@ -1035,7 +1035,7 @@
         break;
     case GCL_HMODULE:
         retval = (LONG)class->hInstance;
-        class->hInstance = newval;
+        class->hInstance = (HINSTANCE)newval;
         break;
     case GCW_ATOM:
         retval = (DWORD)class->atomName;