pkg-config and cross-compiling redux

[Owen Taylor]

There's a long discussion in:

http://pdx.freedesktop.org/cgi-bin/bugzilla/show_bug.cgi?id=130

Between Rüdiger Kuhlmann and me about enhancing pkg-config for cross
compilation. I'd appreciate it if those interested in the subject
would read the bug report and comment (here perhaps, since the bug
report is already reaching bugzilla.mozilla.org proportions.)

To summarize briefly, some of the proposals that are made there
are:

 - Make pkgconfig.m4 use AC_PATH_TOOL so it finds <host>-pkg-config 
   first.

 - When pkg-config is invoked as <host>-pkg-config, have it extract
   the <host> part and substitute it for occurrences of $HOST in
   $PKG_CONFIG_LIBDIR. 

 - Add a $PKG_CONFIG_CROSS_LIBDIR variable to allow configuration
   of cross compilation as above while not disturbing native 
   builds.

 - Add $PKG_CONFIG_DESTDIR ($PKG_CONFIG_CROSS_DESTDIR) variables
   with subtitution as above that would set a $_destdir variable.
   This would allow .pc files to be written so they work either
   on the host or target system.

(These proposals are filtered through my personal preferences;
Rüdiger proposed somewhat different forms that amount to basically
the same thing)

Thanks,
						Owen