php: fix native php when it is from sstate

the native php is used to install the target pear, and native php
has hard-code path, so make wrapper to override the hard-code path

the configuration format of pear.conf for native php is like:
"type:path length:path", path will be replaced when populate sysroot
setscene, but the path length is not changed, and make php unable to
work, add a task to SSTATEPOSTINSTFUNCS to fix the path length

Signed-off-by: Roy Li <rongqing.li@windriver.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>