Minor makefile improvments

Don't rebuild FileRecordTools/FileRecord*.o every time.
Clean version_git.h.

Makefile

@@ -145,7 +145,7 @@ $(UTIL_SUBDIRS) $(SUBDIRS): $(OBJ_DIR) $(BIN_DIR)
 clean:
 	@$(MAKE) --no-print-directory --directory=$(BT_ROOT) clean_api
 	@echo " * Cleaning up."
-	@rm -f $(OBJ_DIR)/* $(BIN_DIR)/*
+	@rm -f $(VERSION_FILE) $(OBJ_DIR)/* $(BIN_DIR)/*
 .PHONY: clean
 
 test: all

src/utils/FileRecordTools/Makefile

@@ -28,7 +28,10 @@ _EXT_OBJECTS=SingleLineDelimTextFileReader.o BamFileReader.o Bed3Interval.o Bed6
 EXT_OBJECTS=$(patsubst %,$(OBJ_DIR)/%,$(_EXT_OBJECTS))
 BUILT_OBJECTS= $(patsubst %,$(OBJ_DIR)/%,$(OBJECTS))
 
-$(BUILT_OBJECTS): $(SOURCES) $(SUBDIRS)
+all: $(BUILT_OBJECTS) $(SUBDIRS)
+.PHONY: all
+
+$(BUILT_OBJECTS): $(SOURCES)
 	@echo "  * compiling FileRecordMgr.cpp"
 	@$(CXX) -c -o $(OBJ_DIR)/FileRecordMgr.o FileRecordMgr.cpp $(LDFLAGS) $(CXXFLAGS) $(INCLUDES)
 	@echo "  * compiling FileRecordMergeMgr.cpp"
@@ -48,4 +51,4 @@ clean:
 	@rm -f $(OBJ_DIR)/FileRecordMergeMgr.o
 	
 
-.PHONY: clean
\ No newline at end of file
+.PHONY: clean