[llvm] RuntimeLibcalls: Split lowering decisions into LibcallLoweringInfo (PR #164987)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `ppc64le-flang-rhel-clang` running on `ppc64le-flang-rhel-test` while building `llvm` at step 6 "test-build-unified-tree-check-flang".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/157/builds/41963

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-unified-tree-check-flang) failure: 1200 seconds without output running [b'ninja', b'check-flang'], attempting to kill
...
PASS: Flang :: Semantics/type-parameter-constant.f90 (3959 of 3969)
PASS: Flang :: Semantics/team_number02.f90 (3960 of 3969)
PASS: Flang :: Semantics/this_image01.f90 (3961 of 3969)
PASS: Flang :: Semantics/symbol24.f90 (3962 of 3969)
PASS: Flang :: Transforms/debug-dwarf-version.fir (3963 of 3969)
PASS: Flang :: Transforms/simplify-fir-operations.fir (3964 of 3969)
PASS: Flang :: Transforms/stack-arrays.f90 (3965 of 3969)
PASS: Flang :: Driver/omp-driver-offload.f90 (3966 of 3969)
PASS: Flang :: Driver/linker-options.f90 (3967 of 3969)
PASS: Flang :: Intrinsics/math-codegen.fir (3968 of 3969)
command timed out: 1200 seconds without output running [b'ninja', b'check-flang'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=3559.728818

```

</details>

https://github.com/llvm/llvm-project/pull/164987