[PATCH] dbghelp: Only check process architecture if we are actually given a process.

[Marvin]

Hi,

While running your changed tests on Windows, I think I found new failures.
Being a bot and all I'm not very good at pattern recognition, so I might be
wrong, but could you please double-check?

Full results can be found at:
https://testbot.winehq.org/JobDetails.pl?Key=44598

Your paranoid android.


=== debian9 (64 bit WoW report) ===

dbghelp:
dbghelp.c:89: Test failed: StackWalk64() failed: 487
dbghelp.c:96: Test failed: got bad return address 0
dbghelp.c:124: Test failed: didn't find stack_walk_thread frame