Replace the CLZ function with a CLZ intrinsic in the Cortex-R4 port layer.

Replace the CLZ function with a CLZ intrinsic in the Cortex-R4 port layer.
Add EDS support in the PIC24 port layer.
Remove unnecessary EHB instructions from PIC32 port.
In the PIC32 port assembly code, replace the &= code with a single ins instruction.

git-svn-id: https://svn.code.sf.net/p/freertos/code/trunk@1814 1d2547de-c912-0410-9cb9-b8ca96c0e9e2