PDB paths are not searched by PE module processor

[ranweiler]

When we process PE modules for disassembly in coverage::pe::process_modules(), we only try to resolve the PDB using the CV filename attr.

Instead, we should ideally search in the same way dbghelp API would, as seen here. In particular, we must make sure that we include the directory containing the PE.

[ranweiler]

Note: this doesn't impact the custom debugger, because that uses symbol handler APIs. This issue is limited to here.

[lzybkr]

The dbghelp API to use is SymFindDebugInfoFileW.

It does require some setup (which our debugger does when asked) - namely calling SymInitializeW and SymLoadModuleExW.

[ranweiler]

Hmm, it looks like SymFindDebugInfoFileW() is only meant for .dbg files.

I think we can accomplish what we want by getting the search path with SymGetSearchPathW(), and then using SymFindFileInPathW() to search for the expected .pdb.

[lzybkr]

Ugh, yes. Not sure how I found the correct api after finding that one, but still linked to the wrong one. Sorry about that.

[lzybkr]

Note that you can pass NULL for the SearchPath and it will pick up the path set from SymInitialize (which we also pass NULL so we pick up the default.)