In a binary processed by COAST, the ext_cmds_cmds variable seems to
take up more space than mentioned in the map file by the linker.

By making the patcher script only modify regions that are large enough
to take the recovery code (which is a good idea, in any case) this
small problematic area is skipped.

As a mitigation measure, unused space in the flash can be filled with
NOPs. At the end of each piece of unused space, a function that
attempts to recover by resetting the stack pointer and restarting the
code is placed. That way, if an SEU corrupts the PC or some function's
return pointer and execution resumes at some region that was supposed
to be empty, the code should have a good chance at restarting
gracefully.

To be used with loadbin in JLinkExe.