Support both "-*-coding:" and "-*- coding:" in magic cookies

Support both "-*-coding:" and "-*- coding:" in magic cookies

The code responsible for checking coding sytem magic cookies in files was
only searching for "-*-coding:...", however most (most == all in SXEmacs,
but in XEmacs and GNU/Emacs most == majority) files that have these
cookies seem to use "-*- coding:...".  This changeset means SXEmacs will
now honour the coding cookie regardless of it being "-*-coding" or
"-*- coding".

	* src/mule/file-coding.c (autodetect_real_coding_system): Look for
	" coding:" as well as "coding:"

Signed-off-by: Steve Youngs <steve@sxemacs.org>