meta-oe: Replace EXCLUDE_FROM_WORLD_libc-musl = "1" with COMPATIBLE_HOST_libc-musl = 'null'
This gives users a proper error message when trying to build
a known non-building package.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Khem Raj <raj.khem@gmail.com>