IDC 5.6.0 regression: Cannot LoadLibrary DLL with dependencies in other folders

Since commit "IDC: Add folder containing DLL to search path for dependencies." 824df695ad99 (https://codereview.qt-project.org/#/c/127118/, QTBUG-48586) introduced in Qt 5.6.0, idc.exe replaced use of plain ::LoadLibrary() with this function:

static HMODULE loadLibraryQt(const QString &input)
{
    if (QSysInfo::windowsVersion() < QSysInfo::WV_VISTA)
        return LoadLibrary((const wchar_t *)input.utf16()); // fallback for Windows XP and older

    // Load DLL with the folder containing the DLL temporarily added to the search path when loading dependencies
    return LoadLibraryEx((const wchar_t *)input.utf16(), NULL,
                         LOAD_LIBRARY_SEARCH_DLL_LOAD_DIR | LOAD_LIBRARY_SEARCH_DEFAULT_DIRS);
}

The result of this is that for Windows Vista and newer %PATH% is no longer checked for dependencies - only the following paths are checked

• [winroot]\system32
• idc.exe application directory
• target dll directory

Not searching $PATH is a regression. The intention of QTBUG-48586 was just to add the target dll directory to the list of searched directories - not to remove other until that point searched directories specified in %PATH%.