[arch-general] Include sbcl sources with a fixed system path

[Daniel White]

Presently the pathname translation for "SYS" is
'/tmp/sbcl/trunk/src/sbcl-1.0.24/'.  This kind of makes it hard for
'M-.' to work well in slime.

This patch for the PKGBUILD generates a modified core with the
translation for "SYS" changed to the '/usr/share/sbcl-source/'.
Basically it means that we can put the 'src' and 'contrib' directories
form the sbcl sources in '/usr/share/sbcl-source/' and the various
source lookup functions in sbcl and slime will work.

This was inspired from Debian's changes to support the
common-lisp-controller which also happens to update the pathname
translations.

The big question is whether or not it is worth splitting the source
into a new package (sbcl-source).  With the source included it
comes to around 13Mb.  Either way the modified core won't cause a
problem since the path is already wrong.

-- 
Daniel White