Consolidate TLS block allocation for static binaries with ld.so

Consolidate TLS block allocation for static binaries with ld.so

Use the same code to compute the TLS block size and its alignment.
The code in elf/dl-tls.c is linked in anyway for all binaries
due to the reference to _dl_tls_static_surplus_init.

It is not possible to call _dl_allocate_tls_storage directly
because malloc is not available in the static case.  (The
dynamic linker uses the minimal malloc at this stage.)  Therefore,
split _dl_tls_block_size_with_pre and _dl_tls_block_align from
_dl_allocate_tls_storage, and call those new functions from
__libc_setup_tls.

This fixes extra TLS allocation for the static case, and apparently
some pre-existing bugs as well (the independent recomputation of
TLS block sizes in init_static_tls looks rather suspect).

Fixes commit 0e411c5d3098982d67cd2d7a233eaa6c977a1869 ("Add generic
'extra TLS'").