linux/scc.h: make uapi linux/scc.h self-contained

Userspace cannot compile <linux/scc.h>

    CC      usr/include/linux/scc.h.s
  In file included from <command-line>:32:0:
  usr/include/linux/scc.h:20:20: error: `SIOCDEVPRIVATE' undeclared here (not in a function)
    SIOCSCCRESERVED = SIOCDEVPRIVATE,
                      ^~~~~~~~~~~~~~

Include <linux/sockios.h> to make it self-contained, and add it to the
compile-test coverage.

Link: http://lkml.kernel.org/r/20191108055809.26969-1-yamada.masahiro@socionext.com
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/uapi/linux/scc.h

@@ -4,6 +4,7 @@
 #ifndef _UAPI_SCC_H
 #define _UAPI_SCC_H
 
+#include <linux/sockios.h>
 
 /* selection of hardware types */
 

usr/include/Makefile

@@ -40,7 +40,6 @@ header-test- += linux/omapfb.h
 header-test- += linux/patchkey.h
 header-test- += linux/phonet.h
 header-test- += linux/reiserfs_xattr.h
-header-test- += linux/scc.h
 header-test- += linux/sctp.h
 header-test- += linux/signal.h
 header-test- += linux/sysctl.h