Revert "Use scope-based memory management for malloc, free, open, close, etc."

This commit introduced a lot of changes and seems to have caused a few
issues, including breaking crc32 generation. Revert it for now with the
intention to reimplement some of the improvements.

This reverts commit 9d7600df51.

qbootctl.cpp

@@ -41,23 +41,17 @@ bool isslotnum(const char* str)
 	return strspn(str, "01") == strlen(str);
 }
 
-static void unexpectedSlot(const char *arg)
-{
-	fprintf(stderr, "Expected slot not '%s'\n", arg);
-	exit(1);
-}
-
 unsigned parseSlot(const char* arg)
 {
 	char *end;
 	int slot;
-	if (!isslot(arg))
-		unexpectedSlot(arg);
-
+	if (!isslot(arg)) {
+		goto fail;
+	}
 	if (isslotnum(arg)) {
 		slot = (int)strtol(arg, &end, 10);
 		if (end == arg)
-			unexpectedSlot(arg);
+			goto fail;
 	} else {
 		switch (arg[0]) {
 		case 'a':
@@ -69,11 +63,17 @@ unsigned parseSlot(const char* arg)
 			slot = 1;
 			break;
 		default:
-			unexpectedSlot(arg);
+			goto fail;
 		}
 	}
 
 	return (unsigned)slot;
+
+fail:
+	fprintf(stderr,
+		"Expected slot not '%s'\n",
+		arg);
+	exit(1);
 }
 
 int usage()