re PR target/47500 (-G0 option not recognized by gnat1)

2014-11-20  Vincent Celier  <celier@adacore.com>

	PR ada/47500
	* back_end.adb (Scan_Back_End_Switches): Skip switch -G and
	its argument.

From-SVN: r217849

gcc/ada/back_end.adb

@@ -232,9 +232,10 @@ package body Back_End is
          Last  : constant Natural  := Switch_Last (Switch_Chars);
 
       begin
-         --  Skip -o or internal GCC switches together with their argument
+         --  Skip -o, -G or internal GCC switches together with their argument.
 
          if Switch_Chars (First .. Last) = "o"
+           or else Switch_Chars (First .. Last) = "G"
            or else Is_Internal_GCC_Switch (Switch_Chars)
          then
             Next_Arg := Next_Arg + 1;