When I attempted to build software using gr-osmosdr
outside of the
gnuradio tree, I had to add the subdirectory ./osmosdr to the include
path in gnuradio-osmosdr.pc otherwise cmake complained it couldn't find
the gnuradio-osmosdr includes.
The bug is in the software you're trying to build.
Software is supposed to use #include <osmocom/source.h> and not
source.h directly ( or more generally osmocom/XXX.h instead of XXX.h
directly)
Cheers,
Sylvain