Remove current directory from DLL searching

By removing the current directory from the search paths for dlls, the
loader is less vulnerable.

loader/loader_windows.c

@@ -77,9 +77,11 @@ void windows_initialization(void) {
         loader_log(NULL, VULKAN_LOADER_INFO_BIT, 0, "Using Vulkan Loader %s", dll_location);
     }
 
+    SetDllDirectory("");  // Remove current directory from default DLL search order
     // This is needed to ensure that newer APIs are available right away
     // and not after the first call that has been statically linked
     LoadLibrary("gdi32.dll");
+    SetDllDirectory(NULL);  // Restores the default search order
 
     wchar_t systemPath[MAX_PATH] = L"";
     GetSystemDirectoryW(systemPath, MAX_PATH);