ctrl_c.c: Do not use macro SA_RESTART for DJGPP.

ctrl_c.c: Do not use macro SA_RESTART for DJGPP.

2016-10-11  Andris Pavenis  <andris.pavenis@iki.fi>

	* ctrl_c.c: Do not use macro SA_RESTART for DJGPP.
	* gsocket.h: Do not support sockets for DJGPP.
	* init.c (__gnat_install_handler): Implememt for DJGPP
	* sysdep.c: Include <io.h> for DJGPP
	(_setmode): Define to setmode for DJGPP
	(__gnat_set_mode): Add implementation for DJGPP
	(__gnat_localtime_tzoff): Use localtime_r for DJGPP
	* terminals.c: Add DJGPP to list of unsupported platforms.
	* env.c (__gnat_clearenv): use _gnat_unsetenv on all entries for DJGPP

From-SVN: r240997