Debugger: Remove false soft assertion on Windows

Some libraries do not provide full names.

For example:
frame={level=\"1\",addr=\"0x2b669230\",func=\"*__GI_abort\",file=\"abort.c
\",fullname=\"\",line=\"117\",from=\"D:/sysroot/octeon17/lib32/libc.so.
6\",language=\"c\"}

Change-Id: Ibd273d451844d467395d8d7708b87f2cfc7a139e
Reviewed-by: Christian Stenger <christian.stenger@theqtcompany.com>
Reviewed-by: hjk <hjk@theqtcompany.com>