Revert "Fix Compile Warnings (#5963)"

This reverts commit b83e16dbdd.

Found regressions like auto orientation didn't work anymore after this change, revert it

src/slic3r/GUI/GLTexture.cpp

@@ -470,6 +470,7 @@ void GLTexture::reset()
 
 bool GLTexture::generate_from_text_string(const std::string& text_str, wxFont &font, wxColor background, wxColor foreground)
 {
+    int w,h,hl;
     return generate_from_text(text_str, font, background, foreground);
 }