[PowerPC] Do not use FISel for calls and TOC-based accesses with PC-Rel
PC-Relative addressing introduces a fair bit of complexity for correctly
eliminating TOC accesses. FastISel does not include any of that handling so we
miscompile code with -mcpu=pwr10 -O0 if it includes an external call that
FastISel does not handle followed by any of the following:
Floating point constant materialization Materialization of a GlobalValue Call that FastISel does handle
This patch switches to SDISel for any of the above.
Differential revision: https://reviews.llvm.org/D86343