php: add build-defs.h to SSTATE_SCAN_FILES it defines path to sysroot where...

php: add build-defs.h to SSTATE_SCAN_FILES it defines path to sysroot where pear.conf is later created

* without this fails in do_install (shr-core-branches is workspace where
  we got SSTATE_MIRROR):
  | [PEAR] PEAR           - installed: 1.9.2
  | Wrote PEAR system config file at:
  /var/lib/jenkins/jobs/shr-core/workspace/shr-core/tmp-eglibc/work/armv7a-vfp-neon-oe-linux-gnueabi/php-5.3.6-r0.0/image//var/lib/jenkins/jobs/shr-core-branches/workspace/shr-core/tmp-eglibc/sysroots/x86_64-linux/etc/pear.conf
  | You may want to add: /usr/lib/php to your php.ini include_path
  | Installing header files:
  /var/lib/jenkins/jobs/shr-core/workspace/shr-core/tmp-eglibc/work/armv7a-vfp-neon-oe-linux-gnueabi/php-5.3.6-r0.0/image/usr/include/php/
  | sed: can't read
  /var/lib/jenkins/jobs/shr-core/workspace/shr-core/tmp-eglibc/work/armv7a-vfp-neon-oe-linux-gnueabi/php-5.3.6-r0.0/image//etc/pear.conf:
  No such file or directory
  | ERROR: Function failed: do_install (see
  /var/lib/jenkins/jobs/shr-core/workspace/shr-core/tmp-eglibc/work/armv7a-vfp-neon-oe-linux-gnueabi/php-5.3.6-r0.0/temp/log.do_install.3783
  for further information)
  NOTE: package php-5.3.6-r0.0: task do_install: Failed
* it also has couple of unpackaged dirs in ${D} (all used in STAGING_DIR_NATIVE)
  WARNING: QA Issue: php: Files/directories were installed but not shipped
  /var
  /var/lib
  /var/lib/jenkins
  /var/lib/jenkins/jobs
  /var/lib/jenkins/jobs/shr-core
  /var/lib/jenkins/jobs/shr-core/workspace
  /var/lib/jenkins/jobs/shr-core/workspace/shr-core
  /var/lib/jenkins/jobs/shr-core/workspace/shr-core/tmp-eglibc
  /var/lib/jenkins/jobs/shr-core/workspace/shr-core/tmp-eglibc/sysroots

Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>