Update libcurl

Engine/lib/curl/docs/INTERNALS.md

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+# curl internals
+
+The canonical libcurl internals documentation is now in the [everything
+curl](https://everything.curl.dev/internals) book. This file lists supported
+versions of libs, tools and operating systems.
+
+## Portability
+
+ We write curl and libcurl to compile with C89 compilers. On 32-bit and up
+ machines. Most of libcurl assumes more or less POSIX compliance but that is
+ not a requirement.
+
+ We write libcurl to build and work with lots of third party tools, and we
+ want it to remain functional and buildable with these and later versions
+ (older versions may still work but is not what we work hard to maintain):
+
+## Dependencies
+
+ We aim to support these or later versions.
+
+ - OpenSSL      0.9.7
+ - GnuTLS       3.1.10
+ - zlib         1.1.4
+ - libssh2      1.0
+ - c-ares       1.16.0
+ - libidn2      2.0.0
+ - wolfSSL      2.0.0
+ - openldap     2.0
+ - MIT Kerberos 1.2.4
+ - GSKit        V5R3M0
+ - NSS          3.14.x
+ - Heimdal      ?
+ - nghttp2      1.12.0
+ - WinSock      2.2 (on Windows 95+ and Windows CE .NET 4.1+)
+
+## Operating Systems
+
+ On systems where configure runs, we aim at working on them all - if they have
+ a suitable C compiler. On systems that do not run configure, we strive to
+ keep curl running correctly on:
+
+ - Windows      98
+ - AS/400       V5R3M0
+ - Symbian      9.1
+ - Windows CE   ?
+ - TPF          ?
+
+## Build tools
+
+ When writing code (mostly for generating stuff included in release tarballs)
+ we use a few "build tools" and we make sure that we remain functional with
+ these versions:
+
+ - GNU Libtool  1.4.2
+ - GNU Autoconf 2.57
+ - GNU Automake 1.7
+ - GNU M4       1.4
+ - perl         5.004
+ - roffit       0.5
+ - groff        ? (any version that supports `groff -Tps -man [in] [out]`)
+
+Library Symbols
+===============
+
+ All symbols used internally in libcurl must use a `Curl_` prefix if they are
+ used in more than a single file. Single-file symbols must be made static.
+ Public ("exported") symbols must use a `curl_` prefix. (There are exceptions,
+ but they are to be changed to follow this pattern in future versions.) Public
+ API functions are marked with `CURL_EXTERN` in the public header files so
+ that all others can be hidden on platforms where this is possible.