Update to mimalloc dev branch

Author: gnzlbg

Cargo.lock

@@ -1831,9 +1831,9 @@ dependencies = [
 
 [[package]]
 name = "mimalloc-sys"
-version = "0.1.5"
+version = "0.1.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b95f8e6d03de63db3537f5e0b59b9ca5247d8d42b1bd8b7db5f36ec49b885351"
+checksum = "4aa3cefb626f6ae3d0b2f71c5378c89d2b1d4d7bc246b0ca9a7ee61a4daad291"
 dependencies = [
  "cc",
  "libc",

src/rustc/Cargo.toml

@@ -22,7 +22,7 @@ rustc_codegen_ssa = { path = "../librustc_codegen_ssa" }
 #features = ['unprefixed_malloc_on_supported_platforms']
 
 [dependencies.mimalloc-sys]
-version = '0.1.5'
+version = '0.1.6-dev'
 optional = true
 
 [features]