MicroChip-SDCC

For pic device libraries and header files which are derived from
Microchip header (.inc) and linker script (.lkr) files Microchip
requires that "The header files should state that they are only to be
used with authentic Microchip devices" which makes them incompatible
with the GPL. Pic device libraries and header files are located at
non-free/lib and non-free/include directories respectively.