Use pipe and sed in configure.ac

[Lyre]

I tried to exact an option from php-config using:

php-config --configure-options | sed -n
's|.*--with-config-file-scan-dir=\([^ ]*\).*|\1|p'

It works on shell, and outputs "/etc/php5/conf.d/" on opensuse.

And I tired it in configure.ac, as following:

PHPINC=`php-config --includes`
PHPCDIR=`php-config --configure-options | sed -n
's|.*--with-config-file-scan-dir=\([^ ]*\).*|\1|p'`

AC_SUBST([PHPINC])
AC_SUBST([PHPCDIR])

After subsitution in Makefile, the PHPCDIR is empty， meanwhile PHPINC get
the correct result.

What' the correct way to use it?