postgresql: fix autoreconf

autoreconf needs to be told where to find macros as the Makefile.am does
not do this.

Signed-off-by: Ross Burton <ross.burton@arm.com>

meta-oe/recipes-dbs/postgresql/postgresql.inc

@@ -133,6 +133,8 @@ def is_target(d):
 export PERLCONFIGTARGET = "${@is_target(d)}"
 export PERL_ARCHLIB = "${STAGING_LIBDIR}${PERL_OWN_DIR}/perl5/${@get_perl_version(d)}/${@get_perl_arch(d)}"
 
+EXTRA_AUTORECONF += "-I config"
+
 do_configure() {
     # do_configure
     autotools_do_configure