fix for make build-dep to update changed dependencies

Makefile

+# Process flags
+ifeq ($(Y), 1)
+	YFLAG=-y
+endif
+
 # Determine Coq version
 COQ_VERSION=$(shell coqc --version | egrep -o 'version 8.[0-9]' | egrep -o '8.[0-9]')
 COQ_MAKEFILE_FLAGS ?=
@@ -28,8 +33,9 @@ Makefile.coq: _CoqProject Makefile
 # Install build-dependencies
 build-dep:
 	cat opam.pins | build/opam-pins.sh
-	opam pin add coq-lambda-rust "$$(pwd)#HEAD" -k git -y -n
-	opam install coq-lambda-rust --deps-only -y
+	opam upgrade $(YFLAG)
+	opam pin add coq-lambda-rust "$$(pwd)#HEAD" -k git -n -y
+	opam install coq-lambda-rust --deps-only $(YFLAG)
 
 # some fiels that do *not* need to be forwarded to Makefile.coq
 Makefile: ;

build/opam-ci.sh

@@ -27,7 +27,7 @@ done
 # Install/upgrade build-dependencies
 echo
 opam upgrade -y
-make build-dep
+make build-dep Y=1
 
 # done
 echo