update build system

Makefile

@@ -17,7 +17,7 @@ clean: Makefile.coq
 
 # Create Coq Makefile. POSIX awk can't do in-place editing, but coq_makefile wants the real filename, so we do some file gymnastics.
 Makefile.coq: _CoqProject Makefile awk.Makefile
-	coq_makefile $(COQ_MAKEFILE_FLAGS) -f _CoqProject -o Makefile.coq
+	coq_makefile -f _CoqProject -o Makefile.coq
 	mv Makefile.coq Makefile.coq.tmp && awk -f awk.Makefile Makefile.coq.tmp > Makefile.coq && rm Makefile.coq.tmp
 
 # Install build-dependencies

build/opam-pins.sh

@@ -4,7 +4,7 @@ set -e
 ## Usage:
 ##   ./opam-pins.sh < opam.pins
 
-if ! which curl; then
+if ! which curl >/dev/null; then
     echo "opam-pins needs curl. Please install curl and try again."
     exit 1
 fi