metadata.dtd: update to latest
ebuild-ipc: use safe cwd for import, bug #469338
ebuild.sh: use PORTAGE_PYM_PATH as default cwd
filter_readonly_variables: safe cwd, bug #469338
check-implicit-pointer-usage: safe cwd bug 469338
dohtml: safe cwd, bug #469338
dohtml: restore cwd for __helpers_die