Don't loose the cppflags added by automake

This includes an -I directive to allow compilation of moxi from
another directory (eg. ../moxi/configure && make )

Change-Id: Ie84242bc12cfaee08e65ac1217fa161473131e9b
Reviewed-on: http://review.membase.org/3222
Reviewed-by: Dustin Sallings <dustin@spy.net>
Tested-by: Dustin Sallings <dustin@spy.net>

Makefile.am

@@ -84,7 +84,7 @@ if BUILD_SOLARIS_PRIVS
 moxi_SOURCES += solaris_priv.c
 endif
 
-moxi_CPPFLAGS = -DCONFLATE_DB_PATH=\"$(CONFLATE_DB_PATH)\"
+moxi_CPPFLAGS = -DCONFLATE_DB_PATH=\"$(CONFLATE_DB_PATH)\" $(AM_CPPFLAGS)
 moxi_LDADD =
 moxi_LDFLAGS = $(LTLIBEVENT) $(LTLIBCONFLATE) $(LTLIBHASHKIT)
 moxi_DEPENDENCIES =