sanitycheck: crashes after test execution summary report are not caught

[nashif]

For example, running tests/net/websocket on qemu_x86:

PROJECT EXECUTION SUCCESSFUL
***** CPU Page Fault (error code 0x00000000)
Supervisor thread read address 0x00000004
PDE: 0x025 Present, Read-only, User, Execute Enabled
PTE: 0x00 Non-present, Read-only, Supervisor, Execute Enabled
Current thread ID = 0x004044d8
eax: 0xffffffff, ebx: 0x00000000, ecx: 0x0000d9dc, edx: 0x00403d18
esi: 0x00000000, edi: 0x00001e79, ebp: 0x00420fb8, esp: 0x00420fb4
eflags: 0x00000286 cs: 0x0008
call trace:
eip: 0x0000769f
     0x00016345 (0x0)
     0x00001e89 (0x4044c0)
Fatal fault in thread 0x004044d8! Aborting.

A short time after PROJECT EXECUTION SUCCESSFUL the system crashes, this is not caught by sanitycheck.