[Positioning] Makefile: call prepare before *.o

When compiling in parallel (make -j), the directory 'obj' was sometimes
created too late (i.e. after the end of the first compilation, so the .o
could not be written on the disk). This is now fixed.

owlps-positioning/Makefile

@@ -113,13 +113,13 @@ SOURCE_TESTS = $(OBJ:$(OBJ_DIR)/%.o=$(TESTS_DIR)/%_test.hh)
 OBJ_TESTS = $(TESTUTIL_OBJ) $(TESTSETUP_OBJ)
 INCLUDES_TESTS = $(TESTS_DIR)/valuetraits.hh
 
-all: prepare $(TARGET)
+all: $(TARGET)
 
 # Generic targets
 $(TESTS_DIR)/%.o: $(TESTS_DIR)/%.cc $(TESTS_DIR)/%.hh
 	$(CXX) $(GXXFLAGS) $(TESTSGXXFLAGS) -o $@ -c $<
 
-$(OBJ_DIR)/%.o: $(SRC_DIR)/%.cc $(SRC_DIR)/%.hh
+$(OBJ_DIR)/%.o: $(SRC_DIR)/%.cc $(SRC_DIR)/%.hh prepare
 	$(CXX) $(GXXFLAGS) -o $@ -c $<
 
 %: $(OBJ_DIR)/%.o
@@ -296,6 +296,7 @@ doc:
 	@$(DOXYGEN) $(DOXYFILE)
 
 prepare:
+	@echo "Preparing compilation..."
 	@$(MKDIR) $(OBJ_DIR)
 
 clean:

owlps-positioning/TODO

@@ -1,7 +1,4 @@
 
-- Fix Makefile
-   The 'prepare' target *must* be called before the *.o targets.
-
 - Write a class for Request::type?
    CalibrationRequest::direction uses a dedicated class Direction, why
    not Request::type? That would simplify writing of the type to