Add -mtls-use-call option to avoid %gs:0 TLS accesses.

Adds an option to the 32-bit code generator to match the 64-bit
variant's behavior of generating calls to __nacl_read_tp rather
than fetches from %gs:0 to begin TLS access sequences.

We'll want this for the builds of newlib and libstdc++ that go into
the integrated runtime.  They have their own uses of TLS, which must
be kept separate from the user-side libc's TLS setup.  We'll reserve
%gs for the user side.


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3 files changed