Bug 1445503 - Use MIN instead of unnecessary CLAMP r=karlt

CLAMP is unnecessary as the minimum acceptable value is 0, and
progressPercent is unsigned. CLAMP can trigger the following warning/error in some builds:
error: comparison of unsigned expression < 0 is always false [-Werror=type-limits]

--HG--
extra : rebase_source : 0dfcf4286a74adac03f7498f1d35fee069528826

widget/gtk/nsWindow.cpp

@@ -7091,10 +7091,10 @@ nsWindow::SetProgress(unsigned long progressPercent)
     return;
   }
 
-  progressPercent = CLAMP(progressPercent, 0, 100);
+  progressPercent = MIN(progressPercent, 100);
 
   set_window_hint_cardinal(GDK_WINDOW_XID(gtk_widget_get_window(mShell)),
                            PROGRESS_HINT,
                            progressPercent);
 #endif // MOZ_X11
-}
+}