In the initial code I missed one level of pointer indirection. Instead
of storing errno in impure_data, _impure_ptr was corrupted.
Only simulator is impacted. Real targets have no OS and no syscalls.
This resolves a bunch of stdio cases from the GCC testsuite:
FAIL->PASS: gcc.c-torture/execute/printf-2.c -O0 execution test
Signed-off-by: Dimitar Dimitrov <dimitar@dinux.eu>
a5cd471c7c