[compiler-rt] [builtins] Fix divtc3.c etc. compilation on Solaris/SPARC with gcc (PR #101662)

[Rainer Orth via llvm-commits]

rorth wrote:

> @rorth Rainer, this change broke the following libcxx'`s lit tests on z/OS:
[...]

Sorry for the failure.

> They all failed since after this change `__divtc3` and `__multc3` are not available. It looks like only `CRT_HAS_F128` macro is defined. which was used originally to guard definitions of those functions.
> 
> On z/OS we don't define CRT_HAD_128BIT and according to this [snippet code](https://github.com/llvm/llvm-project/blob/main/compiler-rt/lib/builtins/int_types.h#L71C1-L76C7) from `int)types.h` Microsoft as well so they might be affected as well.

Me knowing nothing about z/OS and not having access to such a system, could you please provide the output of the compilation of `divtc3.c` with `-g3 -dD -save-temps` added?  Going through the maze of macro definitions was bad enough when I had to on SPARC, on a foreign system it's pure guesswork.

> Would you be able to revert this change and come up with the proper fix for this?

Given that the patch has been in for two weeks without complaint, could you give me a day or two to investigate and come up with a fix?  This avoid the constant churn of Revert/Reland/Re-Revert/Re-Reland.  Thanks.

https://github.com/llvm/llvm-project/pull/101662