Cortex-A5 IAR port baseline prior to removing all SAMA5 specifics to make it generic.:

Cortex-A5 IAR port baseline prior to removing all SAMA5 specifics to make it generic.:
- Slight improvement to the save context macro.
- Remove some #warning remarks.
- Enable interrupts before calling the ISR handler rather than in the ISR handler.

git-svn-id: https://svn.code.sf.net/p/freertos/code/trunk@2284 1d2547de-c912-0410-9cb9-b8ca96c0e9e2