autogen: use pkg-config directly instead of guile-config
The autoconf macros in autogen use dpkg (!) and guile-config to determine
what/where Guile is.
If the build host has an installed guile, these can produce conflicting results.
More interestingly, if the Guile library source and compiled form have bad
timestamps (source newer than compiled) the configure scripts knows that Guile
is present but doesn't know what version it is, resulting in compile errors.
[ YOCTO #3370 (partially) ]
Signed-off-by: Ross Burton <ross.burton@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
