1042 cxx: implement __aeabi_atexit
1042 base: provide a weak init_rtld dummy in base lib

This is needed later to eliminate LDSO specific CRT0 implementations.
1042 ldso: make function get_program_var_addr global

This is needed later to lookup program symbols like ctors and dtors to
eliminate the need for a startup lib in dynamic programs.
1042 os: make program ctors and dtors visible to LDSO

This is needed later when eliminating the need for a startup lib in
dynamic programs to enable LDSO to call ctors and dtors of the program.
1042 ldso: use generic CRT0 files
1042 os: remove startup lib from dynamic programs

All the pre- and post-processing of the startup lib around the main
function of a dynamic program is now done by LDSO. Hence LDSO directly
calls the main function of the program.
1042 test-ldso: test ctors, dtors and atexit functions
1042 hw: ease syscall backends and ready them for -O0

Previously we used to many registers in syscalls with much arguments
to build with optimization level O0. Additionally this fix fastens the
userland backend of syscalls.
1042 hw & arm7: ready CPU driver for -O0