Remove the need for pkgconfig in cmake config

[carstene1ns]

• Untested on windows and macos
• Fixes using of liblcf with psvita toolchain
• Simplifies finding of the library

Fun fact: most of the autotools hackery is only needed for distributions like debian and mageia (hello #341), that put stuff in custom directories.

[Ghabry]

confirmed working on macOS