[oe] Reference to sysroot in PHP packages

[Adam Lee]

On Yocto 1.7.1, running `bitbake php` will show a QA warning:

WARNING: QA Issue: php requires
/media/Build/master/build/tmp/work/cortexa8hf-vfp-neon-poky-linux-gnueabi/php/5.4.36-r0/image/usr/bin/php,
but no providers in its RDEPENDS [file-rdeps]


Doing a grep for sysroot within the packages-split directory shows a number
of references:

root at pine:/media/Build/master/build/tmp/work/cortexa8hf-vfp-neon-poky-linux-gnueabi/php/5.4.36-r0/packages-split#
grep media/Build/master/build/tmp/sysroots/x86_64-linux -r .

./php-pear/usr/bin/pear:  if test
"/media/Build/master/build/tmp/sysroots/x86_64-linux/usr/bin/php" =
'@'php_bin'@'; then
./php-pear/usr/bin/pear:
 PHP="/media/Build/master/build/tmp/sysroots/x86_64-linux/usr/bin/php"
./php-pear/usr/bin/peardev:  if test
"/media/Build/master/build/tmp/sysroots/x86_64-linux/usr/bin/php" =
'@'php_bin'@'; then
./php-pear/usr/bin/peardev:
 PHP="/media/Build/master/build/tmp/sysroots/x86_64-linux/usr/bin/php"
./php-pear/usr/bin/pecl:  if test
"/media/Build/master/build/tmp/sysroots/x86_64-linux/usr/bin/php" =
'@'php_bin'@'; then
./php-pear/usr/bin/pecl:
 PHP="/media/Build/master/build/tmp/sysroots/x86_64-linux/usr/bin/php"

I believe this problem also results in the failure of populate_sdk task.