Build fails with:
> /usr/lib/gcc/powerpc64le-alpine-linux-musl/9.2.0/../../../../powerpc64le-alpine-linux-musl/bin/ld:
> ports_glibc.o: in function `readPort1': ports_glibc.c:(.text+0x130):
> undefined reference to `inb'
> /usr/lib/gcc/powerpc64le-alpine-linux-musl/9.2.0/../../../../powerpc64le-alpine-linux-musl/bin/ld:
> ports_glibc.o: in function `writePort1': ports_glibc.c:(.text+0x178):
> undefined reference to `outb