delete previous $DATADIR/why3 before installing

Makefile.in

@@ -212,6 +212,8 @@ clean::
 
 install_no_local::
 	mkdir -p $(BINDIR)
+	rm -rf $(DATADIR)/why3
+	mkdir -p $(DATADIR)/why3
 	mkdir -p $(DATADIR)/why3/images
 	mkdir -p $(DATADIR)/why3/images/boomy
 	mkdir -p $(DATADIR)/why3/images/fatcow
@@ -235,6 +237,7 @@ install_no_local::
 #	if test -d /etc/bash_completion.d; then cp -f share/bash/why3 /etc/bash_completion.d; fi
 
 install_no_local_lib::
+	rm -rf $(OCAMLLIB)/why3
 	mkdir -p $(OCAMLLIB)/why3
 	cp -f src/why3.cm* $(OCAMLLIB)/why3
 	cp -f META $(OCAMLLIB)/why3

configure.in

@@ -394,7 +394,7 @@ else
                 cp -f src/coq-tactic/coqCompat.8.3.ml src/coq-tactic/coqCompat.ml
                 AC_MSG_RESULT($COQVERSION)
                 ;;
-          8.*|trunk)
+          8.4*|trunk)
 	        enable_coq_support=yes
                 cp -f src/coq-tactic/coqCompat.8.4.ml src/coq-tactic/coqCompat.ml
                 AC_MSG_RESULT($COQVERSION)
@@ -402,7 +402,7 @@ else
           *)
                 enable_coq_support=no
 	        AC_MSG_WARN(You need Coq 8.3 or later; Coq discarded)
-                reason_coq_support=" (need version 8.3 or later)"
+                reason_coq_support=" (version is $COQVERSION but need version 8.3 or higher)"
                 ;;
         esac
     fi