QuickJS-on-Windows support

[srh]

I have merged the QuickJS PR, #6978, into v2.4.x.

It still has not been made working for Windows.

[srh]

PR #7013 merged quickjspp from https://github.com/c-smile/quickjspp .

I have not yet tested this on Windows.

[srh]

The #7074 and #7075 changes have merged Windows support to the branch v2.4.x-windows.

I am currently working on adjusting the c-smile QuickJSpp code so that it is more acceptable, by:

1. omitting all new features in QuickJSpp, such as JSX support and storage support
2. reviewing existing c-smile changes and fixing the problems. For example, quickJSpp has this broken change (which would incorrectly affect 64-bit non-x86 platforms):

#if INTPTR_MAX >= INT64_MAX
+#if defined(__x86_64__)
 #define LIMB_LOG2_BITS 6
 #else
 #define LIMB_LOG2_BITS 5

3. Applying the later commits from bellard/master, such as the bugfix, fixed invalid Array.prototype.push/unshift optimization

I'm not sure if excising JSX and storage support is necessary, because they're enabled by compilation flags. On the other hand, I want the changeset relative to Bellard's quickjs repo to be as small as possible.