musl: Use MUSL_LDSO_PATHS to generate lib search paths file

With this change, the OpenHarmomy lib paths are now added to
/etc/ld-musl-${MUSL_LDSO_ARCH}.path based on the content of the distro
variable MUSL_LDSO_PATHS.

Signed-off-by: Thierry Escande <thierry.escande@huawei.com>