[sanitizer_common] Use GetStaticTlsBoundary on Solaris 11.4

This is a restricted alternative to D91605
<https://reviews.llvm.org/D91605> which only works on Solaris 11.4 SRU 10+,
but would break the build on Solaris 11.3 and Illumos which lack
`dlpi_tls_modid`.

Apart from that, the patch is trivial.  One caveat is that the
`sanitizer_common` and `asan` tests need to be linked explicitly with `ld
-z relax=transtls` on Solaris/amd64 since the archives with calls to
`__tls_get_addr` are linked in directly.

Tested on `amd64-pc-solaris2.11`, `sparcv9-sun-solaris2.11`, and
`x86_64-pc-linux-gnu`.

Differential Revision: https://reviews.llvm.org/D120048