Bugfix: Correct ccan-upstream directory include

ccan.bfg/Makefile.am

@@ -11,4 +11,4 @@ libccan_a_SOURCES = \
 	../ccan-upstream/ccan/opt/private.h  \
 	../ccan-upstream/ccan/opt/usage.c  \
 	../ccan-upstream/ccan/typesafe_cb/typesafe_cb.h
-libccan_a_CPPFLAGS = -I$(top_srcdir)/ccan
+libccan_a_CPPFLAGS = -I$(top_srcdir)/ccan-upstream