Otherwise it leads to error: argument to 'sizeof' in 'memset' call is the same pointer type 'struct usbmsc_lun_s *' as the destination

samv7:twihs driver add reference counting

Approved-by: Gregory Nutt <gnutt@nuttx.org>

configs/.gitignore:  Make sure that any .gdbinit, .project, or .cproject files are ignore so that they are less likely to be included in a patch or PR.

Update tools/configure.c to same functionality as configure.sh.  Add an array of optional file names.  Currently, .gdbinit is the only optional file but other things like IDE-specific project files might need to be copied as well.

Improve configure.sh behavior (proposal).

Approved-by: Gregory Nutt <gnutt@nuttx.org>

 - enable to call from top directory.
 - enable to designate direct path for config.
 - install .gdbinit if the target has.

Fixed typo "CORTEXR5F" in arch/arm/Kconfig

Approved-by: Gregory Nutt <gnutt@nuttx.org>

Fixed ARMv7-M Toolchain definition for Cortex-M4.

Approved-by: Gregory Nutt <gnutt@nuttx.org>

 - Cortex-M4 only have Single Precision FPU.

multiple fixes for stm32f1xx RTC clock

Approved-by: Gregory Nutt <gnutt@nuttx.org>

- compile issues because of missing RTC_MAGIC #defines
- missing functionality based on RTC_MAGIC in RTC based on stm32_rtcounter.c
- IRQ setup from up_rtc_initialize was later reset in up_irqinitialize
- write access to backup registers without enabling access to backup domain
- possible races in set/cancel alarm
tested with STM32F103C8 only
device now wakes up from forced STANDBY mode by alarm

pthreads:  Move pthread_barrier_init, pthread_barrier_destroy, and pthread_barrier_wait from sched/pthreads to libc/pthreads.  This just coordinate other OS interface calls but are not a fundamental OS interfaces and, hence, do not belong within the OS.

pthreads:  Move pthread_cond_init and pthread_cond_destory from sched/pthreads to libc/pthreads.  This just coordinate other OS interface calls but are not a fundamental OS interfaces and, hence, do not belong within the OS.

pthreads:  Move pthread_once from sched/pthreads to libc/pthreads.  pthread_once just coordinates other OS interface calls but is not a fundamental OS interface and, hence, does not belong within the OS.

pthreads:  Move pthread_yield from sched/pthreads to libc/pthreads.  it is a simple wrapper for sched_yield and does not belong within the OS.

Upstream kinetis

Approved-by: Gregory Nutt <gnutt@nuttx.org>

   Initalize SPI1 on connector J6. No real use, as of yet.

testbuild:Added -x to fail build on errors for CI

Approved-by: Gregory Nutt <gnutt@nuttx.org>

   On CI we want to know ASAP of a failure. This adds the
   -x (exit on build failures) option to faclitate that
   behavior.

   Use ${MAKE} ${MAKE_FLAGS} for make invocation.
   When -x is provided change MAKE_FLAGS to
   --silent --no-print-directory and set -e

   Ignore exit status when using grep for checking
   for CONFIG_NXWM=y

mtd/w25: wait for BUSY flag to clear in w25_readid and w25_unprotect.  W25Q128 datasheet says that all instructions expect 'Read Status Register' and 'Erase/Program Suspend' are ignored when BUSY flag in status register is '1'. Therefore wait for busy flag to clear in w25_readid() and w25_unprotect().

stm32/stm32l4 PWM: While attempting to output a 70 MHz square wave from the timer output of a STM32 clocked at 140 MHz (which works fine in baremetal C), I stumbled on what I believe to be an error in arch/arm/src/stm32/stm32_pwm.c.  Line 1304 we are told that

reload = timclk / info->frequency;

which I belive to be incorrect, it should be

reload = timclk / info->frequency - 1;

since starting to count from 0, if I want to output half of the TIM clock, I must count to 1 and not to 2.

Surely enough, the original code did output 140/3=47 MHz, while this correction does allow the output up to 70 MHz.

I am not sure this affects most users generating slow PWM (e.g. PX4) but for frequencies
close to the PCLK, indeed the difference becomes significant.