This patch adds support for the TLS local-exec access model on AIX to allow
for the ability to generate the 32-bit (specifically, non-optimized) code sequence.
This work is a follow up of D149722.
The particular sequence that is generated for this sequence is as follows:
.tc var[TC],var[TL]@le. // variable offset, with the le relocation specifier bla .__get_tpointer() // get the thread pointer, modifies r3 lwz reg1, var[TC](2) // load the variable offset add reg2, r3, reg1 // add the variable offset to the retrieved thread pointer