Adds support for the TLS general dynamic access model to
assembly files on AIX 32-bit.
To generate the correct code sequence when accessing a TLS variable
v, we first create two TOC entry nodes, one for the variable offset, one
for the region handle. These nodes are followed by a PPCISD::TLSGD_AIX
node (new node introduced by this patch).
The PPCISD::TLSGD_AIX node (TLSGDAIX pseudo instruction) is
expanded to 2 copies (to put the variable offset and region handle in
the right registers) and a call to __tls_get_addr.
This patch also changes the way TC entries are generated in asm files.
If the generated TC entry is for the region handle of a TLS variable,
we add the @m relocation and the . prefix to the entry name.
L..C0: .tc .v[TC],v[TL]@m -> region handle L..C1: .tc v[TC],v[TL] -> variable offset