fix makefile

Makefile

 CXX = $(shell wx-config --cxx)
+CXXFLAGS = $(shell wx-config --cxxflags)
+CXXLIBS = $(shell wx-config --libs)
 
 PROGRAM = opennxtestevent
 
-OBJECTS = $(PROGRAM).o
+OBJECTS =  asyncprocess.o $(PROGRAM).o
 
 # implementation
 
 .SUFFIXES:.o .cpp
 
 .cpp.o :
-	$(CXX) -c `wx-config --cxxflags` -o $@ $<
+	$(CXX) -c $(CXXFLAGS) -o $@ $<
 
 all: $(PROGRAM)
 
 $(PROGRAM):     $(OBJECTS)
-	 $(CXX) -o $(PROGRAM) $(OBJECTS) `wx-config --libs`
-
+	 $(CXX) -o $(PROGRAM) $(OBJECTS) $(CXXLIBS)
 clean:
 	 rm -f *.o $(PROGRAM)