dynamic get QueryFullProcessImageNameA for XP support

[lynnux]

this is for gnu build on xp.

btw, the msvc build not use libbacktrace, it use dbghelp, but the dbhelp.dll on XP lack those functions:

SymInitializeW
SymFromAddrW
SymGetLineFromAddrW64
SymFromInlineContextW
SymGetLineFromInlineContextW

which seems a lot work to do, the easy solution for msvc build is to combined a newer version of dbghelp.dll with exe on xp.

[alexcrichton]

Thanks!

I think though the behavior that we'll want here is that if QueryFullProcessImageName isn't available we fail to load a filename entirely on Windows. The semantics of QueryFullProcessImageName are what we want in that it returns the current path of the executable rather than GetModuleFileName which I believe returns the original path to the executable (before any renames happened, if any)

[lynnux]

Ok, GetModuleFileName removed

[alexcrichton]

Thanks!