All GCC final arch/*/src/Makefiles: Allow --start-group and --end-group to be redefined for the case where GCC is used to link (instead of LD).  Suggested by Paul Alexander Patience.

wfi.mac should be copied into the directory with the IAR project. Then set it to "Options -> Debugger -> Setup macro file(s)". This will allow debugging via JTAG when calling the WFI instruction.

Merged in david_s5/nuttx-1/david_s5/kconfig-edited-online-with-bitbucket-1463078993637 (pull request #19)

Kconfig edited online with Bitbucket

sam_xdmac.c edited online with Bitbucket

sam_xdmac.c edited online with Bitbucket

Since I can't (yet) get rid of the sanity checks in config.h, I suppose I should at least update the checks.

Backout d5be40be.  This change is logically correct but unmasks a lot of issues.  Reverted for now.