fixed rust bindings

bindings/const_generator.py

bindings/rust/.gitignore

bindings/rust/Cargo.toml

bindings/rust/examples/asm.rs

bindings/rust/src/arm64_const.rs

bindings/rust/src/arm_const.rs

bindings/rust/src/ffi.rs

bindings/rust/src/hexagon_const.rs

bindings/rust/src/keystone_const.rs

bindings/rust/src/lib.rs

bindings/rust/src/mips_const.rs

bindings/rust/src/ppc_const.rs

bindings/rust/src/sparc_const.rs

bindings/rust/src/systemz_const.rs

bindings/rust/src/x86_const.rs

bindings/rust/tests/keystone.rs