build: Make `Makefile` more generic

module:

	make -C /vm/9pfs/lkm-arch/root/lib/modules/6.0.8-arch1-1-tinyvm/build M=$(PWD) modules

hax: build-hax_read build-hax_exec build-set_cr

build:

	mkdir build

hax: hax_read hax_exec set_cr

build/hax_read.o: build src/hax_read.c

	gcc -o build/hax_read.o -c src/hax_read.c

hax_read: build/hax_read.o

	gcc -o hax_read build/hax_read.o

hax_exec: src/hax_exec.c

	gcc -o hax_exec src/hax_exec.c

build/%.o: src/%.c build

	gcc -o $@ -c $<

set_cr:

	gcc -o set_cr src/set_cr.c

build-%: build/%.o

	gcc -o $* $?