Better test for lpsolve55 Makefiles being called correctly (lib prefix empty on Windows).

git-svn-id: https://www.prismmodelchecker.org/svn/prism/prism/trunk@6224 bbc10eb1-c90d-0410-af57-cb519fbb1720

prism/ext/lp_solve_5.5_java/Makefile

@@ -11,7 +11,7 @@ all: checks lpsolve55java
 
 # Try and prevent accidental makes (i.e. called manually, not from top-level Makefile)
 checks:
-	@if [ "$(LIBPREFIX)" = "" ]; then \
+	@if [ "$(LIBSUFFIX)" = "" ]; then \
 	  (echo "Error: This Makefile is designed to be called from the main PRISM Makefile"; exit 1) \
 	fi; 
 

prism/ext/lpsolve55/Makefile

@@ -22,7 +22,7 @@ all: checks ../../lib/$(LIBPREFIX)lpsolve55$(LIBSUFFIX)
 
 # Try and prevent accidental makes (i.e. called manually, not from top-level Makefile)
 checks:
-	@if [ "$(LIBPREFIX)" = "" ]; then \
+	@if [ "$(LIBSUFFIX)" = "" ]; then \
 	  (echo "Error: This Makefile is designed to be called from the main PRISM Makefile"; exit 1) \
 	fi;