Minor mods common files to fix warnings generated by Renesas compiler.

Minor mods common files to fix warnings generated by Renesas compiler.
Correct the header comments in het.c and het.h (RM48/TMS570 demo) which were corrupt.
Correct version numbers in RX63N Renesas compiler demo.
Ensure stacks set up for tasks in the RX200 port layer end on 8 byte boundaries (was 4, which didn't matter but didn't match the definition).
Replaced unqualified (unsigned) in calls to standard functions with (size_t).

git-svn-id: https://svn.code.sf.net/p/freertos/code/trunk@1848 1d2547de-c912-0410-9cb9-b8ca96c0e9e2