Replacing loop over instructions by loop over uses (#189)

Replacing loop over instructions by loop over uses when running the
`lowerGCAllocBytesLate` function.

Merge with mmtk/julia#74.

Author: udesou

mmtk/Cargo.toml

@@ -11,7 +11,7 @@ edition = "2018"
 [package.metadata.julia]
 # Our CI matches the following line and extract mmtk/julia. If this line is updated, please check ci yaml files and make sure it works.
 julia_repo = "https://github.com/mmtk/julia.git"
-julia_version = "ddc7361dec25ec618b75e5eb99bea8e59cbdaeaa"
+julia_version = "67b2ec10542c9e80d1f5b4aeddb8bf9d3c4f6ba1"
 
 [lib]
 crate-type = ["cdylib"]