Latest checkin breaks the freebsd build

[bakul]

This is commit fc6710c04c783df -- this needs to be undone.

[bakul]

$ gmake
echo "#define KBUILD_DATE" 2019-12-30 >src/kbuild.h
cc -g -O3    -c -o src/main.o src/main.c
cc -g -O3   src/main.o -o k
src/main.o: In function `main':
/home/bakul/kona/src/main.c:6: undefined reference to `kinit'
/home/bakul/kona/src/main.c:7: undefined reference to `args'
/home/bakul/kona/src/main.c:8: undefined reference to `attend'
cc: error: linker command failed with exit code 1 (use -v to see invocation)
gmake: *** [Makefile:103: k] Error 1

Don't see why platform specific package build related stuff should clutter up the makefile. Let that be handled on each OS externally (sort of how freebsd ports work).