[AC21.5] Fix syntax error in last patch

APPROVE COMMIT 21.5

Earth to Steve: nobody's that good -- test *everything*.  Especially
the trivial shell stuff.

diff -r b2709239b1f6 ChangeLog
--- a/ChangeLog	Mon May 04 14:32:22 2015 +0900
+++ b/ChangeLog	Tue May 05 04:04:35 2015 +0900
@@ -1,3 +1,8 @@
+2015-05-05  Stephen J. Turnbull  <[email protected]>
+
+	* configure.ac (PostgreSQL): Fix shell syntax error.
+	* configure: Regenerate.
+
 2015-05-04  Stephen J. Turnbull  <[email protected]>
 
 	* configure.ac (PostgreSQL): Allow specification of subdir.
diff -r b2709239b1f6 configure.ac
--- a/configure.ac	Mon May 04 14:32:22 2015 +0900
+++ b/configure.ac	Tue May 05 04:04:35 2015 +0900
@@ -3700,6 +3700,7 @@
 
   if test -n "$pg_header_dir" -a "$header_dir" != "$pg_header_dir"; then
     AC_WARN([--with-postgresql="$pg_header_dir" specified but not found; using "$libpq_fe_h_file"])
+  fi
 
   pq_libs=
   extra_libs=