optee: os: toolchains would include linux target macros likes __linux__

[Randy Li]

Hello

I wonder why Optee OS would use a linux target toolchains but not a bare 
metal target(none os)?

gcc-arm-10.3-2021.07-x86_64-aarch64-none-linux-gnu/bin/aarch64-none-linux-gnu-gcc 
-dM -E - < /dev/null|grep linux
#define __linux 1
#define __gnu_linux__ 1
#define linux 1
#define __linux__ 1

That makes hard to share a header files between Linux kernel and Optee.  
We like to pass some structure in SHM, but optee don't have all those 
Linux types likes <linux/types.h>.

If optee didn't choose the toolchains for the Linux, we could easily 
decide which part would use for Client Agent(Linux kernel) side or TEE 
OS side.

Why we don't use bare metal toolchains ?


Thank you

Randy Li