NuttX upgrade cmake wrapper (#7873)

* NuttX cmake

* px4_macros:Pass the stringified predicate as second arg to static assert

   CC_ASSERT mapes to the c++ static_assert or provides the same
   funtionality for c via the other macros. The c++ static assert
   takes 2 argumants the prdicate and a message. This fixes the
   lacking second argument.

* Updated nuttx and apps submodule to upstream nuttx 7.21+==master

   This is the latest uptake of upstream nuttx and apps.

* ROMFS generate with xxd instead of objcopy

* delete nuttx-patches

* NuttX update submodules to latest px4_nuttx-master

* fix nuttx apps and board dependency

* docker_run update to latest container 2017-08-29

* cmake ROMFS portable sed usage

* NuttX update submodules to latest px4_nuttx-master