TESTS: Enable test_glibc_thread_support.c on Mac OS X

Signed-off-by: Robin Hack <hack.robin@gmail.com>
uwrap: Add more authors to AUTHORS file.

Signed-off-by: Robin Hack <hack.robin@gmail.com>
uwrap: Small uwrap_init optimalization.

Don't call libc_getuid/getgid function twice.

Signed-off-by: Robin Hack <hack.robin@gmail.com>
uwrap: Extend support for syscalls called from threads or main process.

We must distinguish if syscall is called from main process or from
thread.

TESTS:
	Added new test test_real_sync_setuid to
	test_glibc_thread_support.c.

	Extend test_syscall_setreuid.

Signed-off-by: Robin Hack <hack.robin@gmail.com>
uwrap: Extend support for set/getgroups libc functions and syscalls.

Support reflection of groups to main process and add more thread
support.

TESTS:
	Added new test test_sync_setgroups which cover changes in code.
	This test is almost same as test_sync_setgid but is aimed to setgroups
	functions.

Signed-off-by: Robin Hack <hack.robin@gmail.com>