build: get rid of INCLUDES, use AM_CPPFLAGS

INCLUDES in configure.ac was not used at all, and INCLUDES in
Makefile.am is supposed to be AM_CPPFLAGS these days.

Reduces warnings spewed during bootstrap/autoreconf.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
Acked-by: Greg Troxel <gdt@ir.bbn.com>
Acked-by: Feng Lu <lu.feng@6wind.com>
Acked-by: Paul Jakma <paul@jakma.org>
diff --git a/pimd/Makefile.am b/pimd/Makefile.am
index 7173a23..f13debd 100644
--- a/pimd/Makefile.am
+++ b/pimd/Makefile.am
@@ -34,7 +34,7 @@
 PIM_DEFS += -DPIM_ENFORCE_LOOPFREE_MFC
 #PIM_DEFS += -DPIM_UNEXPECTED_KERNEL_UPCALL
 
-INCLUDES = @INCLUDES@ -I.. -I$(top_srcdir) -I$(top_srcdir)/lib
+AM_CPPFLAGS = -I.. -I$(top_srcdir) -I$(top_srcdir)/lib
 DEFS = @DEFS@ -DSYSCONFDIR=\"$(sysconfdir)/\" $(PIM_DEFS)
 INSTALL_SDATA=@INSTALL@ -m 600
 LIBS = @LIBS@