maint: Prefer AM_CPPFLAGS over INCLUDES

Our use of INCLUDES in Makefile.am hearkens back to when we had to
cater to automake 1.9.6 (thanks, RHEL 5) which lacked AM_CPPFLAGS.
Modern Automake flags a warning that INCLUDES is deprecated, and
now that we mandate RHEL 7 or better (see commit c1bc9c66), we no
longer have to cater to the old spelling.  This change will also
make it easier to do per-binary CPPFLAGS.

Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>

examples/Makefile.am

@@ -33,7 +33,8 @@ EXTRA_DIST = \
 	$(wildcard $(srcdir)/xml/test/*.xml)
 
 
-INCLUDES = -I$(top_builddir)/include -I$(top_srcdir)/include -I$(top_srcdir) \
+AM_CPPFLAGS = \
+	-I$(top_builddir)/include -I$(top_srcdir)/include -I$(top_srcdir) \
 	-I$(top_builddir)/gnulib/lib -I$(top_srcdir)/gnulib/lib
 LDADD = $(STATIC_BINARIES) $(WARN_CFLAGS) $(COVERAGE_LDFLAGS) \
 	$(top_builddir)/src/libvirt.la $(top_builddir)/gnulib/lib/libgnu.la \

src/Makefile.am

@@ -25,7 +25,7 @@ abs_topsrcdir = $(shell cd $(top_srcdir) && pwd)
 # No libraries with the exception of LIBXML should be listed
 # here. List them against the individual XXX_la_CFLAGS targets
 # that actually use them.
-INCLUDES =	-I../gnulib/lib \
+AM_CPPFLAGS =	-I../gnulib/lib \
 		-I$(top_srcdir)/gnulib/lib \
 		-I$(top_srcdir) \
 		-I../include \

tests/Makefile.am

@@ -24,7 +24,7 @@ abs_topsrcdir = $(shell cd $(top_srcdir) && pwd)
 
 SHELL = $(PREFERABLY_POSIX_SHELL)
 
-INCLUDES = \
+AM_CPPFLAGS = \
 	-I$(top_builddir) -I$(top_srcdir) \
 	-I$(top_builddir)/gnulib/lib -I$(top_srcdir)/gnulib/lib \
 	-I$(top_builddir)/include -I$(top_srcdir)/include \
@@ -63,7 +63,7 @@ QEMULIB_LDFLAGS = \
 	-rpath /evil/libtool/hack/to/force/shared/lib/creation \
 	$(MINGW_EXTRA_LDFLAGS)
 
-INCLUDES += \
+AM_CPPFLAGS += \
 	-DTEST_DRIVER_DIR=\"$(top_builddir)/src/.libs\"
 
 PROBES_O =

tools/Makefile.am

@@ -15,7 +15,7 @@
 ## License along with this library.  If not, see
 ## <http://www.gnu.org/licenses/>.
 
-INCLUDES = \
+AM_CPPFLAGS = \
 	-I$(top_builddir)/include -I$(top_srcdir)/include \
 	-I$(top_builddir)/gnulib/lib -I$(top_srcdir)/gnulib/lib \
 	-I$(top_builddir)/src -I$(top_srcdir)/src \