exewrapper: report name of failed DLL in error message This uses C string literal concatenation. Example output: $ hg version abort: failed to load Python DLL python27.dll Note that HGPYTHONLIB does not contain the trailing .dll, which works here because the documentation of LoadLibrary [1] says, that if no file name extension is specified in the filename parameter, the default library extension .dll is appended. See [2] for a motivation of this change. [1] https://msdn.microsoft.com/en-us/library/windows/desktop/ms684175(v=vs.85).aspx [2] https://selenic.com/pipermail/mercurial/2015-August/048627.html