#64 Connot link against sidplay2 without libtool

[Leandro Nini]

The Libs definition in pkg-config files are wrong so it is not possible to link against sidplay2 when not using libtool.
They should be:

Libs: -L${libdir} -lsidplay2

for libsidplay2 and:

Libs: -L${libdir} -lsidutils

for libsidutils.