use own naive bdiff tool instead of diff/fc

test/Makefile

@@ -3,9 +3,26 @@
 
 MAKE := make --no-print-dir
 
-.PHONY: all clean
+ifneq ($(shell echo),)
+  CMD_EXE = 1
+endif
 
-all:
+ifdef CMD_EXE
+RM := del /f
+EXE := .exe
+else
+RM := rm -f
+EXE :=
+endif
+
+.PHONY: dotests clean
+
+all: dotests
+
+bdiff:
+	@$(CC) -o bdiff$(EXE) bdiff.c
+
+dotests: bdiff
 	@$(MAKE) -C val clean all
 	@$(MAKE) -C ref clean all
 	@$(MAKE) -C err clean all
@@ -16,4 +33,4 @@ clean:
 	@$(MAKE) -C ref clean
 	@$(MAKE) -C err clean
 	@$(MAKE) -C misc clean
-
+	@$(RM) bdiff$(EXE)