* sysdeps/mach/hurd/i386/init-first.c: Replace PIC #ifdefs with SHARED.

* sysdeps/mach/hurd/i386/init-first.c: Replace PIC #ifdefs with SHARED.

	(init1): Don't initialize __environ here, since init already does it.
	(first_init): New function, broken out of _init.
	(_hurd_stack_setup): Use it.
	[SHARED] (_dl_init_first): New function, renamed from old _init.
	(init1) [SHARED]: Don't call posixland_init here.
	(posixland_init): Take ENVP arg, so signature is usual for initializer.
	[SHARED] (_init): Define as alias for posixland_init.
	[! SHARED] (__libc_first_init): Define as alias for posixland_init.
	* sysdeps/i386/dl-machine.h (RTLD_START): Insert the macro
	RTLD_START_SPECIAL_INIT before calling initializers.
	(RTLD_START_SPECIAL_INIT): Define to empty if undefined.
	* sysdeps/mach/hurd/i386/dl-machine.h: New file.
	* sysdeps/mach/hurd/dl-sysdep.c (_dl_init_first): New weak function.
	* elf/Versions ({libc,ld.so}: GLIBC_2.2): Add _dl_init_first.