[RFA/ARM]: Patch to workaround ARM1176 BLX (immediate) Thumb to ARM issue

[Nick Clifton]

Hi Matthew,

> * When the option is on the linker will only use BLX if the target
> architecture (derived from the object files) is v6T2, v7, or
> greater.

This does not seem right to me.  The erratum only applies to the 
ARM1176JZ-S and ARM1176JZF-S processors and only to Thumb BLX 
instructions.  Disabling the use of BLX in ARM mode or for pre-ARM11 
cores will generate needlessly larger code.

Also when you check the Tag_CPU_arch value, please use the enum names, 
not the integer values.

Cheers
   Nick