pipe-filter-gi, pipe-filter-ii: better use of 'inline' * lib/pipe-filter-aux.c: New file. * lib/pipe-filter-aux.h (PIPE_FILTER_AUX_INLINE): New macro. Replace all uses of 'static inline' with it. Use _GL_INLINE_HEADER_BEGIN, _GL_INLINE_HEADER_END. * lib/pipe-filter-gi.c (filter_init, filter_cleanup) (filter_retcode): No real need for inline here. * modules/pipe-filter-gi, modules/pipe-filter-ii: (Files): Add lib/pipe-filter-aux.c. (Depends-on): Add extern-inline. (configure.ac): Do not require AC_C_INLINE. (lib_SOURCES): Add pipe-filter-aux.c.