Summary:
Update to clang-15 compiler and libraries as clang-12 is ancient.
The changes to oilgen are necessary because the new internal toolchain is being more picky about linking PIC to PIC. In certain modes we build with PIC, but try to link a non-PIC oilgen artifact. Add the ability to build the oilgen artifacts with PIC which sorts this.
Reviewed By: ttreyer
Differential Revision: D46220858
As we now store ContainerInfo objects in OICodeGen::Config, we can not
copy it any more. Change all places that took copies to take const
references instead.
The copy in OICodeGen modified membersToStub, the contents of which form
part of OICache's hash. However, as OICache also previously had its own
copy, it would not have been OICodeGen's modifications.
