Set rustc flags.

Author: hoolioh

src/native/.cargo/config.toml

@@ -0,0 +1,8 @@
+[build]
+rustflags = ["-C", "relocation-model=pic"]
+
+[target.'cfg(target_os = "windows")']
+rustflags = ["-C", "relocation-model=pic", "-C", "target-feature=+crt-static"]
+
+[target.'cfg(all(target_os = "linux", target_env = "musl"))']
+rustflags = ["-C", "relocation-model=pic", "-C", "target-feature=+crt-static"]