This reverts commit cc514d7791dae0808124249ff545d9dda39b24b7.
* It introduced a regression.
https://github.com/apache/incubator-nuttx/issues/3868
* It seems conceptually wrong to have per-process data in
the main thread's stack.
I not two problems in handling of the return error values in PR #3858:
1. In KERNEL mode, the error return value of _SEM_WAIT() will be a negated errno value; in all other modes, it will be -1 (ERROR) with the errno variable set. This must be handled in the test of the returned value: Don't compare with -1; rather check if < 0
2. Also, conversion of the returned value to a negated errno value must be handled differently. This is handled by replacing -get_errno() with the macro _ERRVAL(ret)
This effects only error handling (it fixes it) and no other impacts are expected.
