Subprocess::StartDetached fails on Linux

[rhymu8354]

• [13:16] Neui: Ok I am trying to debug the SystemAbstraction SubprocessDetach test and it fails because it creates an child that exit(0), but WEXITSTATUS() returns 1 .....
• [13:19] Neui: One problem I've found is that you need to check WIFEXITED() before using WEXITSTATUS() (but in this case WIFEXITED() returns 1 so it should be OK)
• [13:26] Neui: You are also doing exit(0) or exit(-1) but WEXITSTATUS returns 1 (no minux, no 255)
• [13:28] Neui: I once debugged that child and when it exit(0), the test still failed