fix rust bindings build on windows (#1584)

Refine rust bindings.

bindings/rust/Cargo.toml

@@ -1,37 +0,0 @@
-[package]
-name = "unicorn-engine"
-version = "2.0.0-rc6"
-authors = ["Ziqiao Kong", "Lukas Seidel"]
-documentation = "https://github.com/unicorn-engine/unicorn/wiki"
-edition = "2021"
-include = [
-    "/.gitmodules",
-    "/COPYING",
-    "/Cargo.toml",
-    "/README.md",
-    "/src/*",
-    "build.rs",
-]
-license = "GPL-2.0"
-readme = "README.md"
-repository = "https://github.com/unicorn-engine/unicorn/"
-description = "Rust bindings for the Unicorn emulator with utility functions"
-build = "build.rs"
-links = "unicorn"
-
-[dependencies]
-bitflags = "1.3"
-libc = "0.2"
-
-[build-dependencies]
-reqwest = { optional = true, version = "0.11", features = ["blocking"] }
-flate2 = { optional = true, version = "1.0" }
-tar = { optional = true, version = "0.4" }
-bytes = { optional = true, version = "1" }
-pkg-config = { optional = true, version = "0.3" }
-
-[features]
-default = ["build_unicorn_cmake"]
-
-use_system_unicorn = ["pkg-config"]
-build_unicorn_cmake = ["reqwest", "flate2", "tar", "bytes"]