tests: regress: add another test case for -idirafter ordering (noticed on pkg-config bugzilla)

Makefile.am

@@ -55,6 +55,7 @@ EXTRA_DIST =	pkg.m4 \
 		tests/lib1/omg-uninstalled.pc \
 		tests/lib1/isystem.pc \
 		tests/lib1/idirafter.pc \
+		tests/lib1/idirafter-ordering.pc \
 		tests/lib1/depgraph-break.pc \
 		tests/lib1/cflags-whitespace.pc \
 		tests/lib1/cflags-whitespace-trailing.pc \

tests/lib1/idirafter-ordering.pc

@@ -0,0 +1,4 @@
+Name: Bad
+Description: Demonstrates problems with -idirafter in old pkg-config; see also https://bugs.freedesktop.org/show_bug.cgi?id=23480
+Version: 1
+Cflags: -I/opt/bad/include1 -idirafter -I/opt/bad/include2 -I/opt/bad/include3

tests/regress.sh

@@ -21,6 +21,7 @@ tests_init \
 	isystem_munge_sysroot \
 	idirafter_munge_order \
 	idirafter_munge_sysroot \
+	idirafter_ordering \
 	pcpath \
 	sysroot_munge
 
@@ -170,6 +171,14 @@ idirafter_munge_sysroot_body()
 		pkgconf --cflags idirafter
 }
 
+idirafter_ordering_body()
+{
+	export PKG_CONFIG_PATH="${selfdir}/lib1"
+	atf_check \
+		-o inline:"-I/opt/bad/include1 -idirafter -I/opt/bad/include2 -I/opt/bad/include3  \n" \
+		pkgconf --cflags idirafter-ordering
+}
+
 pcpath_body()
 {
 	export PKG_CONFIG_PATH="${selfdir}/lib2"