Gentoo's Bugzilla –
Attachment 854942 Details for
Bug 898080sys-libs/libieee1284-0.2.11-r8 fails to compile (MUSL-CLANG-SYSTEM): access_io.c:151:3: error: call to undeclared function outb_p; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]