Add apps/include to include path in top-level Make.defs file.  Remove multiple definitions of INCDIR opt.

Recent enhancements to cmd_ps trips a floating point exception if LIBC_FLOATINGPOINT is not defined (at least on Cortex M4 w/ hardfloat).  I’m using a buildroot gcc configured to support Cortex-M4F and the hard float ABI, target files are compiles with: -mcpu=cortex-m4 -mthumb -mfpu=fpv4-sp-d16 -mfloat-abi=hard.  I’m not sure the best way to address this, but the attached patch file is the first that comes to mind.  Note, I added the float qualifier ‘F’ after a few constants to prevent the compiler from promoting the multiplication and division to double (expensive on M4F) then demoting to single float for the store.  (sorry, it’s one of my many pet peeves ;)
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The NTP client will now optionally use pool.ntp.org as the NTP server; and reset the retry count upon success -- more robust.

apps/canutils/libcanard: Define CANARD_ASSERT as DEBUGASSERT

apps/canutils/libcanard: Update version

Take 2

This reverts commit 0e4c247e.

Allow stack usage to be disabled on contrained systems

Remove references to CONFIG_SYSLOG in nshlib

apps/system/hex2bin:  Move the portable library portion of hex2bin to nuttx/libc/hex2bin where it can be shared with the OS internals.