Fix duplicate suggestions after an ambiguous command
So far lldb is printing this when it finds an ambiguous command:
(lldb) g Ambiguous command 'g'. Possible matches: gdb-remote gui gdb-remote gui
The duplicates come from the fact that we call the same query twice with the same parameters
and add it to the same list. This patch just removes the second query call to GetCommandObject.
As GetCommandObject is const and the name parameter is also not modified, this shouldn't break
anything else. I didn't merge the remaining if statement into the else as I think otherwise the
if obj==nullptr do X else Y pattern in there becomes hard to recognize.
Reviewed By: davide
Differential Revision: https://reviews.llvm.org/D49866