[GNC-dev] Crash during OFX import

[jean laroche]

Devs,

I noticed a crash during OFX import of investment related transactions, 
which only happens in the master branch (not in maint). I have the fix, 
the crash is caused by an uninitialized pointer so it's a simple fix.
I guess it's unusual to have a crash on master and not maint, and bug 
fixes are normally on maint not master.
In any case, I'll do a PR for this, unless you tell me that's not the 
right way to do it.

Thanks

Jean