Correct some problems with SAM3/4 watchdog driver.  Includes some small improvements.  From Max Neklyudov.

drvers/sensor and include/nuttx/sensors: Add support to Bosch BMP180 barometer.  From Alan Carvalho de Assis.

STM32 F7 Ethernet:  Add cache operations to make sure we have data coherency when accessing all DMA-related data

gethostbyname() and gethostbyname_r() should be built even if there is no host file support.  From Sebastien Lorquet

Move definition of h_errno from lib_parsehostfile.c to lib_netdb.  h_errno should still be defined even if there is no host file support.  From  Sebastien Lorquet.