use own naive bdiff tool instead of diff/fc

test/bdiff.c

@@ -0,0 +1,28 @@
+
+// minimal tool to compare two binaries
+
+#include <stdlib.h>
+#include <stdio.h>
+
+int main(int argc, char *argv[])
+{
+    FILE *f1, *f2;
+    if (argc < 3) {
+        return EXIT_FAILURE;
+    }
+    f1 = fopen(argv[1], "rb");
+    f2 = fopen(argv[2], "rb");
+    if ((f1 == NULL) || (f2 == NULL)) {
+        return EXIT_FAILURE;
+    }
+    for(;;) {
+        if (feof(f1) && feof(f2)) {
+            return EXIT_SUCCESS;
+        } else if (feof(f1) || feof(f2)) {
+            return EXIT_FAILURE;
+        }
+        if (fgetc(f1) != fgetc(f2)) {
+            return EXIT_FAILURE;
+        }
+    }
+}