selinux-h: better 'inline'

selinux-h: better 'inline'

* lib/se-context.c, lib/se-selinux.c: New files.
* lib/getfilecon.c (map_to_failure): Omit 'inline' for static function.
* lib/se-context.in.h (SE_CONTEXT_INLINE):
New macro.  Replace all uses of 'static inline' with it.
Use _GL_INLINE_HEADER_BEGIN, _GL_INLINE_HEADER_END.
* lib/se-selinux.in.h (SE_SELINUX_INLINE):
New macro.  Replace all uses of 'static inline' with it.
Use _GL_INLINE_HEADER_BEGIN, _GL_INLINE_HEADER_END.
* modules/selinux-h (Files, lib_SOURCES):
Add lib/se-context.c, lib/se-selinux.c.
(Depends-on): Add extern-inline.
(configure.ac): Do not require AC_C_INLINE.