symboldatabase: Remove unneeded check

scope1 cannot be null at that point of time. If it were, the program
would have crashed, before (it's dereferenced ->)
This commit doesn't just remove dead code, but eliminates a tricky bug,
possibly introduced by over-optimizing compilers:
An explanation why the compiler could produce bad code here is found at
http://blog.regehr.org/archives/970

This commit was enabled by http://css.csail.mit.edu/stack/

Signed-off-by: Stefan Beller <stefanbeller@googlemail.com>