* cygheap.cc (cygheap_fixup_in_child): Drop call to set_dll_dir.

	* cygheap.cc (cygheap_fixup_in_child): Drop call to set_dll_dir.
	(init_cygheap::init_installation_root): Set installation_dir_len.
	(setup_cygheap): Drop call to set_dll_dir.
	* cygheap.h (struct init_cygheap): Add installation_dir_len member.
	(init_cygheap::set_dll_dir): Remove.
	* environ.cc (win_env::add_cache): Use stpcpy for speed.
	(posify_maybe): Use tmp_pathbuf buffer instead of stack.
	(raise_envblock): New function to resize Windows environment block.
	(build_env): Fix indentation.  Call raise_envblock function.  Check if
	$PATH exists and is non-empty.  If not, add PATH variable with Cygwin
	installation directory as content to Windows environment.  Explain why.

	* uinfo.cc (cygheap_pwdgrp::_nss_init): Fill UNICODE_STRING members
	on the fly.  Drop call to RtlInitUnicodeString.
	(pwdgrp::check_file): Ditto.