"Global register variable not supported " build failure(s) — clang 2.9

Global register variable are not supported by clang. This code will fail to build with clang:
register void *ptr asm("rbx") ;
PackageVersionSupposed error messageFull log Bug report
clisp 1:2.49-8lispbibl.d:9107:30: error: global register variables are not supported n/a
qemu-kvm 0.14.1+dfsg-4exec.h:31:30: error: global register variables are not supported Log

2 errors