Resolve "current master not building on ubuntu 16.04 using --with-libtool --enable-developer" also on Windows

See merge request !730

Resolve "building with libtool requires either pic or dlopen to be enabled"

Closes #495

See merge request !704

Resolve "current master not building on ubuntu 16.04 using --with-libtool --enable-developer"

Closes #509

See merge request !727

and remove handcrafted code that enabled __EXTENSIONS__ and _GNU_SOURCE

silence "missing print.h" warning

See merge request !723

Remove broken @ISC_IPV6_H@ placeholder from Makefile.in

See merge request !720

Set sndbuf

See merge request !74

Resolve "rndc reconfig now performs stat() for all zones"

Closes #276

See merge request !518

rndc reconfig should not touch already loaded zones, some refactoring of dns_{zone,view,zt}_{async,}load

Remove isc_keyboard family of functions

See merge request !718

5023.   [cleanup]       Remove isc_keyboard family of functions. [GL #178]

Resolve "Use and require atomic primitives support"

Closes #10

See merge request !657

5023.	[func]		Replace custom assembly for atomic operations with
			atomic support from the compiler. The code will now use
			C11 stdatomic, or __atomic, or __sync builtins with GCC
			or Clang compilers, and Interlocked functions with MSVC.
			[GL #10]

This properly orders clearing the freed pointer and calling isc_refcount_destroy
as early as possible to have ability to put proper memory barrier when cleaning
up reference counting.

Directly use return value of atomic_compare_exchange_strong_explicit insteaf of comparing expected value