main/musl: various fixes from git master, and packaging fixes

- use upstream commits for all arm pie/unwind fixes
- replace getopt with BSD licensed GNU compatible getopt
- set proper SONAME for the libc generated for packaging purposes
- rename libc.so to be ld-musl-$ARCH.so.1 and point the SONAME
  and ldd links to it. this allows libc.so to go to -dev package
  as it will be used for compiling only.
- move specs file to musl-crosstool subpackage