The v9.0 PPC64LE cross-compilation backport (SERVER-136667, https://github.com/10gen/mongo/pull/64292, commit 6240b023a57b197466df8ad1fc04265cd1d37d75) selects the ARM64-hosted LLD bundled with the published PPC GCC cross archive. That archive revision, 1bce2cbf33a4c08af2e73c3b2084e282ca76f3f5, contains MongoDB LLD 23.1.0, whereas native v9.0 PPC release builds use the branch's pinned v5 LLD 19.1.7.

PPC is intended to use LLD. Preserve its existing linker version when moving compilation to ARM64, rather than upgrade the linker as part of the host change.

Requested change:

• Select ARM64-hosted LLD 19.1.7 from the existing @mongo_toolchain_v5 repository for PPC cross links on RHEL 8, 9, and 10.
• Keep PPC GCC 14.2 and the existing target-runtime/sysroot pins.
• Update GCC -B search paths and declare the LLD executable and supporting files as link-action inputs; avoid selecting bundled LLD 23 or a host-installed linker.
• Preserve s390x linker behavior and other platforms.

Validation:

• Add regression coverage for the resolved linker search path and declared link inputs.
• Build the PPC cross-toolchain smoke target and archive_dist_test/archive_dist_test_debug on the three RHEL target variants.
• Verify aquery/link command and executable .comment identify MongoDB LLD 19.1.7.
• Run native PPC tests and compare binary metadata/assembly with native artifacts.

The corresponding open v8.3 backport is being corrected in https://github.com/10gen/mongo/pull/64525. The before/after v8.3 artifact comparison confirmed LLD 19.1.7 versus 23.1.0 in .comment; v9.0 selects the identical published PPC archive. Removed runtime tracing probes and target-header drift are separate issues outside this ticket's linker-version scope.