Add directives to force stop unwinding.

On aarch64/x86/x86_64 add a macro that inserts a cfi directive that will
stop unwinding.

For arm, clang doesn't allow emitting .cantunwind, so add a comment and
leave it the same as it current is.

Add this macro to __libc_init and __start_thread.

Also, remove duplicate compilation of libc_init_static.cpp that already
includes the static library that includes that file.

Bug: 15469122

Test: Did unwinds using new unwinder tool (unwind) and debuggerd -b
Test: and verified new unwinder works on aarch64/x86/x86_64.
Test: Verified that it works on old unwinder for aarch64/x86, but
Test: x86_64 doesn't work properly, but as well as before.
Change-Id: I77302e8f6c7ba1549d98a4a164106ee82c9ecadc