teach proto_c to look in the source directory for out of tree builds

diff --git a/lib/dns/Makefile.in b/lib/dns/Makefile.in
index 7a182f143d9fc0bf4bb37c33dd7a6dc610a1eefe..eb3346af2c414a25eb896712425dfb044a57d3dc 100644 (file)
--- a/lib/dns/Makefile.in
+++ b/lib/dns/Makefile.in
@@ -205,7 +205,7 @@ ${OBJS}: include
 dnstap.@O@: dnstap.c dnstap.pb-c.c
 
 dnstap.pb-c.c dnstap.pb-c.h include/dns/dnstap.pb-c.h: dnstap.proto
-       $(PROTOC_C) --c_out=. dnstap.proto
+       $(PROTOC_C) --c_out=. --proto_path ${srcdir} dnstap.proto
        cp -f dnstap.pb-c.h include/dns
 
 dnstap.pb-c.@O@: dnstap.pb-c.c