x86_64 only:
	* gendef (_sigfe_maybe): Drop pushing %r12, use %r10 instead since we
	don't call yield anymore.
	(_sigfe): Ditto.
	(_sigbe): Ditto.
	* fhandler.h (class fhandler_dev_random): Change type of pseudo to
	uint32_t to make sure it's 32 bit on all supported platforms.
	* globals.cc (__isthreaded): New global variable.  Explain what it's
	used for.
	* miscfuncs.cc (thread_wrapper): Set __isthreaded to 1 here.
	* Makefile.in (DLL_OFILES): Add arc4random.o.
	* common.din: Export arc4random, arc4random_addrandom, arc4random_buf,
	arc4random_stir and arc4random_uniform.
	* mktemp.cc (arc4random): Remove static replacement function.
	* posix.sgml (std-bsd): Add arc4random functions.
	* include/cygwin/stdlib.h: Declare arc4random functions.
	* include/cygwin/version.h (CYGWIN_VERSION_API_MINOR): Bump.
	* libc/arc4random.cc: New file implementing arc4random functions taken
	from FreeBSD.
	Add missing ChangeLog entry for former checkin.
	* new-features.sgml (ov-new1.7.19): Add arc4random,
	arc4random_addrandom, arc4random_buf, arc4random_stir and
	arc4random_uniform.