[PATCH libgloss/arm] discourge the use of blx when it's not supported

[Nick Clifton]

Hi Bin, Hi Carl,

   Sorry for the delay in reviewing this patch - I was on vacation.

   Anyway I have looked over the patch, and it is fine.  I have checked 
it in, along with a slightly expanded changelog entry:

Cheers
   Nick

libgloss/ChangeLog
2011-09-29  Bin Cheng  <bin.cheng@arm.com>

	* arm/arm.h (HAVE_CALL_INDIRECT): Define.
         * arm/crt0.S (indirect_call): New macro.  Encodes indirect
	function calls.  Does not use blx for pre-armv5 targets.