Replaced whole bunch for Makefiles with a single generic Makefile.

- Targeting GNU toolchain.
- Modern dependency handling.
- Warning-free build.
- GCC option -Werror set.
- Dynamic search paths.
- Don't write into source directories.
- Easy cleanup by just removing 'wrk'.

src/Makefile

@@ -0,0 +1,76 @@
+PROGS = ar65  \
+        ca65  \
+        cc65  \
+        cl65  \
+        co65  \
+        da65  \
+        grc65 \
+        ld65  \
+        od65  \
+        sp65
+
+CA65_INC := $(abspath ../asminc)
+CC65_INC := $(abspath ../include)
+LD65_LIB := $(abspath ../lib)
+LD65_OBJ := $(abspath ../lib)
+LD65_CFG := $(abspath ../cfg)
+
+CFLAGS += -MMD -MP -O -std=c89 -I common \
+          -Wall -Wextra -Wno-char-subscripts -Werror \
+          -DCA65_INC=$(CA65_INC) -DCC65_INC=$(CC65_INC) \
+          -DLD65_LIB=$(LD65_LIB) -DLD65_OBJ=$(LD65_OBJ) -DLD65_CFG=$(LD65_CFG)
+
+all: $(PROGS)
+
+mostlyclean:
+	$(RM) -r ../wrk
+
+clean: mostlyclean
+	$(RM) -r ../bin
+
+.PHONY: all $(PROGS) mostlyclean clean
+
+##########
+
+define OBJS_template =
+
+$(1)_OBJS := $$(addprefix ../wrk/,$$(addsuffix .o,$$(basename $$(wildcard $(1)/*.c))))
+
+$$($(1)_OBJS): | ../wrk/$(1)
+
+../wrk/$(1):
+	mkdir -p $$@
+
+DEPS += $$($(1)_OBJS:.o=.d)
+
+endef
+
+##########
+
+define PROG_template =
+
+$$(eval $$(call OBJS_template,$(1)))
+
+../bin/$(1): $$($(1)_OBJS) ../wrk/common/common.a | ../bin
+	$$(CC) $$(LDFLAGS) -o $$@ $$^
+
+$(1): ../bin/$(1)
+
+endef
+
+##########
+
+../wrk/%.o: %.c
+	@echo $(CC) $<
+	@$(CC) -c $(CFLAGS) -o $@ $<
+
+../bin:
+	mkdir $@
+
+$(eval $(call OBJS_template,common))
+../wrk/common/common.a: $(common_OBJS)
+	$(AR) r $@ $^
+
+$(foreach prog,$(PROGS),$(eval $(call PROG_template,$(prog))))
+
+-include $(DEPS)