PX4-NuttX/nuttx branch test: px4-master_auto_rebase

NuttX:
 - https://github.com/PX4-NuttX/nuttx/tree/px4-master_auto_rebase
 - PX4/NuttX@bf1c17f

Changes from PX4-NuttX/nuttx (PX4/NuttX@d5c12b2) in current PX4/master (ceae2f8)
PX4/NuttX@d5c12b2...bf1c17f

bf1c17f (HEAD, origin/px4-master_auto_rebase) [PX4: WIP] Fix transmission status handling in the serial interrupt
a50c739 [PX4: REJECTED] cstdint fix
5f1565e [PX4: REJECTED] add math.h
4769335 [PX4: WIP] Jenkinsfile
29474a2 (origin/master) Trivial update to some comments and debug statement formats.
0a4091b Merged in masayuki2009/nuttx.nuttx/lc823450_posix_spawn (pull request #683)
367965b Merged in masayuki2009/nuttx.nuttx/lc823450_parallel_build (pull request #682)
c6450fa Refresh some configurations.
664af2a Default for CONFIG_EXECFUNCS_HAVE_SYMTAB should be 'not set'
dae6d95 configs/lc823450-xgevk/src: Eliminate some warnings.  drivers/usbhost:  Update comments.

Apps:
 - https://github.com/PX4-NuttX/apps/tree/px4-master_auto_rebase
 - PX4/NuttX-apps@336dc3a

Changes from PX4-NuttX/apps (PX4/NuttX-apps@36806ba) in current PX4/master (ceae2f8)
PX4/NuttX-apps@36806ba...336dc3a

336dc3a (HEAD -> px4-master_auto_rebase, origin/px4-master_auto_rebase) [REJECTED] add-var-expansion-in-nsh-parse.patch
7c1082b (origin/master) apps/examples/nsh:  Clean up some rather complex conditional compilation associated with the previous commit.
0ea260e apps/examples/nsh:  Add logic to automatically register an application symbol table as part of NSH initialization.
6b93881 Merged in masayuki2009/nuttx.apps/fix_helloxx (pull request #144)
654ee7e apps/examples/elf, module, posix_spawn:  Correct naming of global variables that violations the naming requirements of the coding standard.
db9c56e apps/examples/powerled:  Eliminate a warning about an uninitialized variable.
e66470d Merged in raiden00/apps (pull request #143)
db77b1e apps/examples/tcpblaster:  Fix an error in time calculation.
19b8a52 apps/examples/tcpblaster/tcpblaster_server.c:  Start time was not being initialized on the server side on the first pass through loop so the first output record had a crazy time.
749eccb Squashed commit of the following: