Fix build in separate build directory

* cfg.mk: use $(srcdir)/ prefix for Makefile.nonreentrant include
* examples/domain-events/events-c/Makefile.am tools/Makefile.am
  examples/hellolibvirt/Makefile.am: extend the include paths to
  use $(top_srcdir)/include too.

cfg.mk

@@ -101,7 +101,7 @@ sc_prohibit_VIR_ERR_NO_MEMORY:
 	msg='use virReportOOMError, not V'IR_ERR_NO_MEMORY		\
 	  $(_prohibit_regexp)
 
-include Makefile.nonreentrant
+include $(srcdir)/Makefile.nonreentrant
 sc_prohibit_nonreentrant:
 	@fail=0 ; \
 	for i in $(NON_REENTRANT) ; \

examples/domain-events/events-c/Makefile.am

-INCLUDES = -I@top_srcdir@/include
+INCLUDES = -I$(top_builddir)/include -I$(top_srcdir)/include
 noinst_PROGRAMS = event-test
 event_test_CFLAGS = $(WARN_CFLAGS)
 event_test_SOURCES = event-test.c

examples/hellolibvirt/Makefile.am

-INCLUDES = -I@top_srcdir@/include
+INCLUDES = -I$(top_builddir)/include -I$(top_srcdir)/include
 noinst_PROGRAMS = hellolibvirt
 hellolibvirt_CFLAGS = $(WARN_CFLAGS)
 hellolibvirt_SOURCES = hellolibvirt.c

tools/Makefile.am

@@ -43,7 +43,7 @@ virsh_LDADD =							\
 		$(VIRSH_LIBS)
 virsh_CFLAGS = 							\
 		-I$(top_srcdir)/gnulib/lib -I../gnulib/lib	\
-		-I../include					\
+		-I../include -I$(top_srcdir)/include		\
 		-I$(top_srcdir)/src				\
 		-I$(top_srcdir)/src/util			\
 		-DGETTEXT_PACKAGE=\"$(PACKAGE)\"		\