Minor fix to remove redundancy in load modules
Minor fix to remove redundancy in load modules

Use the existing getFilenameKey() to get the key of load module and filename.
Rationale: In very rare cases, prof doesn't find the mangled name of a procedure (not sure why?), so it's possible to have two identical procedures from different files.

HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit,HPCToolkit/hpctoolkit