PX4-NuttX/nuttx branch test: px4-master_auto_rebase

NuttX:
 - https://github.com/PX4-NuttX/nuttx/tree/px4-master_auto_rebase
 - PX4/NuttX@dd15f53

Changes from PX4-NuttX/nuttx (PX4/NuttX@8957a02) in current PX4/master (afe82ff)
PX4/NuttX@8957a02...dd15f53

dd15f53 (HEAD, origin/px4-master_auto_rebase) [PX4: WIP] Fix transmission status handling in the serial interrupt
12de1a7 [PX4: REJECTED] cstdint fix
9539993 [PX4: REJECTED] add math.h
551d3bc [PX4: WIP] Jenkinsfile
d77df92 (origin/master) Trivial FATFS cleanup
b75103e Update some comments.
9289055 drivrs/mmcsd:  Partial reversion of commit 17b6c7b.  Backed out all block callback logic controlled CONFIG_SDIO_BLK_CALLBACK.  Usage of this feature by applications is a blatant violation of the POSIX interface standard.
17b6c7b drivers/mmcsd/mmcsd_sdio.c:  Fix an error that was causing SDIO multiple block transfers from achieving full performance.  Also adds a feature controlled by  CONFIG_SDIO_BLK_CALLBACK that bypasses the normal mechanism for obtaining sector data for transfer.
f9f56aa  arch/arm/src/stm32f7/:  Fix data timeout errors with multiblock transfers.
4e92314 Update some comments

Apps:
 - https://github.com/PX4-NuttX/apps/tree/px4-master_auto_rebase
 - PX4/NuttX-apps@ef32b6c

Changes from PX4-NuttX/apps (PX4/NuttX-apps@36806ba) in current PX4/master (afe82ff)
PX4/NuttX-apps@36806ba...ef32b6c

ef32b6c (HEAD -> px4-master_auto_rebase, origin/px4-master_auto_rebase) [REJECTED] add-var-expansion-in-nsh-parse.patch
f0b4f14 (origin/master) Eliminate some new warnings reported in build testing.
3cc79be examples/lvgldemo/ and graphics/littlevgl/:  pdate LVGL to version 5.1.1
1030ea7 Merged in masayuki2009/nuttx.apps/fix_mksymtab (pull request #147)
cb9e951 apps/Make.defs:  Improve the symtab target.  tools/mksymtab.sh:  Fix a typo.
296f583 apps/tools:  Forgot to include a file with last commit.
272bdc0 apps Makesystem:  Fix an error when building apps/ withtout nuttx/, using only the NuttX export package only and assuming that the nuttx/ directory in not even present.  In this case, the problem fixed where the apps/Make.defs file was selecting tools from the /tools directory which does not exist because TOPDIR=apps/import.  Instead, for this build case, I have not thought of any option but to duplicate scripts as necessary in the apps/tools directory.  Also added a top-level target to compile the symbol table.  Misc fixes: quoting in scripts, some errors in script syntax.
9240ef5 Merged in masayuki2009/nuttx.apps/fix_symtab_related (pull request #146)
4db29bc apps/examples/elf:  Correct some Kconfig coments.
2ecc94f apps/import/Makefile:  Eliminate a MAKE sytax error that occurs in some (but not environments) when symtab.c has not been generated.