Fix a regression with nested @finally not being
called, introduced in 1.4.7 release.

Big thanks to David Chisnall for a swift fix in GNUStep Objective C
runtime.

Add unit tests for two Objective C runtime properties:
nested finally handling and ability to catch C++ exceptions.

Manually resolve conflicts (new ObjC runtime).

Conflicts:
	mod/box/index.h

under Mac OS (unreasonable stalls), changing to the subprocess.communicate with the same
functonality

Lua tests don't pass though.

gcc interpretation of -fno-inline has changed between 4.6.1 and 4.6.3.

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