Apple Objective C runtime expects that objects passed
to object_setClass are first bzeroed.

Conflicts:
	connector/perl/t/data/init.lua

Use -Wno-bitwise-op-parentheses only if the compiler has them.

Do not use bundled libobjc on Darwin.
Refactor cmake scritps: introduce os.cmake, arch.cmake,
compiler.cmake, libobjc.cmake, luajit.cmake.

Remove the hack with building libobjc/luajit as a
dependency on cfg.

Do not specify -ggdb when compiling with clang.

Add -fno-objc-legacy-dispatch and -fobjc-nonfragile-abi
when compiling with CLang on Linux.

Remove -fgnu-runtime when compiling with gcc on Mac.

Many minor cleanups.

Conflicts:
	connector/perl/lib/MR/Tarantool/Box.pm
	connector/perl/t/03-box.t
	connector/perl/t/data/init.lua

Conflicts:
	connector/perl/t/03-box.t

Conflicts:
	connector/perl/t/03-box.t