package: use <pkg>_CONFIG_SCRIPTS in packages that used special handling

The packages changed by this commit were not only changing prefix= and
exec_prefix= during their <foo>-config fixups, they were also changing
includedir= and/or libdir=. So, they could not be directly converted
to the new <pkg>_CONFIG_SCRIPTS infrastructure.

However, a careful analysis of their default <foo>-config shows that
includedir= and libdir= is defined relatively to either ${prefix} and
${exec_prefix}. Therefore, the manual fixing of includedir= and
libdir= is useless, and fixing prefix= and exec_prefix=, as done by
the <pkg>_CONFIG_SCRIPTS mechanism is sufficient.

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Acked-by: "Samuel Martin" <s.martin49@gmail.com>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>