build: Fix lirc version detection when cross compiling.
build: Fix lirc version detection when cross compiling.

The setup.py script that runs on the host can't use the client library
built for target. So setup.py falls back to a wrong hard-coded VERSION
value.

Instead of importing the target library, use exec() to read
lirc/config.py directly for its VERSION value.

Fixes build failure:

/usr/bin/install -c -m 644 ./python-pkg/dist/lirc-0.10.0.tar.gz \
    '.../output/host/arm-buildroot-linux-musleabihf/sysroot/usr/share/lirc'
/usr/bin/install: cannot stat './python-pkg/dist/lirc-0.10.0.tar.gz': \
    No such file or directory

stb-tester/lirc,stb-tester/lirc,stb-tester/lirc,stb-tester/lirc,stb-tester/lirc,stb-tester/lirc