Get Pkg.build() working on Mac (#13)

* Get `Pkg.build()` working on Mac

* fixup! Get `Pkg.build()` working on Mac

Author: nickrobinson251

deps/build.jl

@@ -41,7 +41,11 @@ run(`which cargo`)
 assert_compatible_version(`cargo -V`, "1.55.0")
 rust_source = joinpath(@__DIR__, "rust_store")
 # Elide rust warnings - they aren't helpful in this context
-ENV["RUSTFLAGS"]="-Awarnings"
+if Sys.isapple()
+    ENV["RUSTFLAGS"]="-Awarnings -Clink-arg=-undefined -Clink-arg=dynamic_lookup"
+else
+    ENV["RUSTFLAGS"]="-Awarnings"
+end
 # build release
 cd(rust_source)
 if Sys.islinux() || Sys.isapple()