ewok_rlw.h: add missing 'inline' to function definition

ewok_rlw.h: add missing 'inline' to function definition

The 'ewok_rlw.h' header file contains the rlw_get_run_bit() function
definition, which is marked as 'static' but not 'inline'. At least when
compiled by gcc, with the default -O2 optimization level, the function
is actually inlined and leaves no static version in the ewah_bitmap.o
and ewah_rlw.o object files. Despite this, add the missing 'inline'
keyword to better describe the intended behaviour.

Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>