add last changes to bash file

feasibility_analysis/perform_feasibility_analysis.sh

@@ -2,10 +2,9 @@
 
 #build storm
 cd storm
-if [ -d "build" ]; then
-	rm -r -y build
+if [ ! -d "build" ]; then
+	mkdir build
 fi
-mkdir build
 cd build
 cmake .. 
 make