Merge Pull Request from: @zhengzengkai 
 
This set of patches backport rust for Linux feature.
Provide a rust runtime environment in the kernel and support subsystems such as modules, 
device drivers, and networks. Some examples are also provided.

[Testing]
To easliy check whether the requirements are met
Make LLVM=1 rustavailable
Read Documentation/rust/quick-start.rst for a quick start.

CONFIG:
CONFIG_RUST
CONFIG_SAMPLES_RUST
CONFIG_SAMPLE_RUST_CHRDEV
....

Supported platforms: x86_64 and ARM64 
 
Link:https://gitee.com/openeuler/kernel/pulls/44 
Reviewed-by: Xie XiuQi <xiexiuqi@huawei.com> 
Signed-off-by: Xie XiuQi <xiexiuqi@huawei.com>