feat: add mbedtls 3.6.1 descriptor

xpkg V1 + mcpp Form B descriptor for `mbedtls 3.6.1`. Targets the C
language compile rule introduced in mcpp 0.0.2: `library/*.c` (108
sources) compile via `c_object` (gcc/clang sibling driver, c11) and
archive into a single `libmbedtls.a` covering crypto + x509 + ssl —
matching what xmake's `add_packages("mbedtls")` produces.

Glob-aware paths (`*/library/*.c`, `*/include`, `*/library`) absorb
the GitHub tarball's `mbedtls-mbedtls-3.6.1/` wrap layer.

Verified locally: a smoke project depending on `mbedtls = "3.6.1"`
builds, links statically (musl), runs, and produces the FIPS 180-4
SHA-256 vector for "abc" correctly.

First downstream consumer is mcpplibs/tinyhttps (parallel PR adds an
`mcpp.toml` that depends on this descriptor).

Author: Sunrisepeak

pkgs/m/mbedtls.lua

@@ -0,0 +1,50 @@
+-- M6.x glob-aware Form B descriptor for mbedtls.
+--
+-- Pure-C library; relies on mcpp 0.0.2's C-language compile rule (`.c`
+-- routed to `c_object` via the gcc/clang sibling driver). Produces a
+-- single static archive `libmbedtls.a` that bundles all of mbedtls's
+-- crypto + x509 + ssl translation units — the same arrangement xmake's
+-- mbedtls package emits when used by `add_packages("mbedtls")`.
+
+package = {
+    spec        = "1",
+    name        = "mbedtls",
+    description = "An open source, portable, easy to use, readable and flexible TLS library, and reference implementation of the PSA Cryptography API",
+    licenses    = {"Apache-2.0"},
+    repo        = "https://github.com/Mbed-TLS/mbedtls",
+    type        = "package",
+
+    xpm = {
+        linux = {
+            ["3.6.1"] = {
+                url    = "https://github.com/Mbed-TLS/mbedtls/archive/refs/tags/mbedtls-3.6.1.tar.gz",
+                sha256 = "db75d2f7f35e29cf09f7bd6734d8ee3325f29c298ef071350c5e70a40dd4f0f9",
+            },
+        },
+        macosx = {
+            ["3.6.1"] = {
+                url    = "https://github.com/Mbed-TLS/mbedtls/archive/refs/tags/mbedtls-3.6.1.tar.gz",
+                sha256 = "db75d2f7f35e29cf09f7bd6734d8ee3325f29c298ef071350c5e70a40dd4f0f9",
+            },
+        },
+        windows = {
+            ["3.6.1"] = {
+                url    = "https://github.com/Mbed-TLS/mbedtls/archive/refs/tags/mbedtls-3.6.1.tar.gz",
+                sha256 = "db75d2f7f35e29cf09f7bd6734d8ee3325f29c298ef071350c5e70a40dd4f0f9",
+            },
+        },
+    },
+
+    -- Form B `mcpp` segment: paths are globs relative to the verdir
+    -- (~/.mcpp/registry/data/xpkgs/<idx>-x-mbedtls/<ver>/). The leading
+    -- `*/` absorbs the GitHub tarball's `mbedtls-mbedtls-3.6.1/` wrap.
+    mcpp = {
+        language     = "c++23",                   -- the [package].standard knob; mcpp uses it for the C++23 toolchain.
+        import_std   = false,                     -- pure C lib — no std module.
+        sources      = { "*/library/*.c" },       -- 108 sources, all of crypto + x509 + ssl.
+        include_dirs = { "*/include", "*/library" },
+        c_standard   = "c11",
+        targets      = { ["mbedtls"] = { kind = "lib" } },
+        deps         = { },
+    },
+}