MSVC: Restore support for non-incremental linking without 'rc' in PATH

Since commit 0b552eb877 (MSVC: Embed manifests directly for
non-incremental vs_link_exe links, 2023-02-20, v3.27.0-rc1~438^2) we
tell the MSVC `link` tool to embed manifests directly rather than
running `mt` ourselves.  However, `link` expects `rc` to be in the PATH
when embedding manifests.  Although that is normally true, some users
prepare minimal environments and explicitly specify include and link
directories for the Windows SDK.  In such cases, `rc` is not in the PATH
and is explicitly specified in `CMAKE_RC_COMPILER`.  Restore support for
such cases by explicitly adding the RC location to the end of the PATH.

Fixes: #25047