Update and fix forking and finalization

Updated the revision of the `ruby` repo to include bug fixes:

-   Close dead mutators after forking to mitigate the problem of forking
    while having multiple threads.
-   Drain final jobs after GCs triggered by allocation.  Also drain
    final jobs at exit before forcing `obj_free`.

Also updated the version of mmtk-core.

mmtk/Cargo.toml

@@ -12,7 +12,7 @@ edition = "2021"
 # Metadata for the Ruby repository
 [package.metadata.ci-repos.ruby]
 repo = "mmtk/ruby" # This is used by actions/checkout, so the format is "owner/repo", not URL.
-rev = "8082532b9f720a1e7508ac32641dcfbbf51dd518"
+rev = "1c4102e7bcee03f66ca72f916cde0d2bd7a8638b"
 
 [lib]
 name = "mmtk_ruby"
@@ -37,7 +37,7 @@ features = ["is_mmtk_object", "object_pinning", "sticky_immix_non_moving_nursery
 
 # Uncomment the following lines to use mmtk-core from the official repository.
 git = "https://github.com/mmtk/mmtk-core.git"
-rev = "f78523616ea4989148f60c0943bd2c6cae364339"
+rev = "160b7702fccda133c9407234821ad35103623179"
 
 # Uncomment the following line to use mmtk-core from a local repository.
 # path = "../../mmtk-core"