when pthread exits or is cancelled, mutexes held by thread are marked inconsistent and the highest priority thread waiting for the mutex is awakened.

pthreads: Partial implementation of final part of robust mutexes: Keep list of all mutexes held by a thread in a list in the TCB.

pthread: Fix return value of pthread_give/takesemaphore().  Add option to pthread_takesemaphore to ignore EINTR or not.

pthreads: Add more robustness characteristics: pthread_mutex_lock() and trylock() will now return EOWNERDEAD if the mutex is locked by a thread that no longer exists.  Add pthread_mutex_consistent() to recover from this situation.

STM32 COMP cosmetics

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

Add COMP character driver

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

configs/clicker2-stm32:  Cleans up minor issues

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

Add ffsl(), ffsll(), fls(), flsl(), flsll() and use GCC's __builtin_ctz/__builtin_clz for faster implementation of these

I needed to use DS3231, I remember that in past it worked ok, but now for stm32f4xx is used another driver (chip specific, stm32f40xxx_i2c.c) and DS3231 driver doesn't work. After investigating a problem I found that I2C driver (isr routine) has a few places there it sends stop bit even if not all messages are managed. So, e.g., removing stm32_i2c_sendstop (#1744) and adding stm32_i2c_sendstart after data reading helps to make DS3231 working.  Verified by David Sidrane.

The interrupt occurs over the counter overflow

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

fix compile error when disabled the flash data cache corruption for stm32 f1xx

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

stm322_flash:missing unlock on F1 HSI off path

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

stm32_i2c_alt:Move def of regval to top func def per CS

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