## Summary
A lot of linker scripts were listed twice, once for unix, once for windows.
This PR cleans up the logic so they're only listed once.
## Impact
Any opportunity to use a single source of truth and reduce lines of code is a win!
## Testing
CI will test all build
This reverts commit 45672c269d.
Because:
* It's very confusing to have cc as LD.
* I don't see what "-nostartfiles -nodefaultlibs" in LDFLAGS are
supposed to do when we use LD directly. It would be simpler to
remove them from our LDFLAGS.
Drop to user-space in kernel/protected build with up_pthread_exit,
now all pthread_cleanup functions executed in user mode.
* A new syscall SYS_pthread_exit added
* A new tcb flag TCB_FLAG_CANCEL_DOING added
* up_pthread_exit implemented for riscv/arm arch
Signed-off-by: Huang Qi <huangqi3@xiaomi.com>
