GH-142234: Allow `--enable-wasm-dynamic-linking` under WASI (GH-142235)

While CPython doesn't support `--enable-wasm-dynamic-linking`, external tools like componentize-py do and they have to patch around it. Since the flag is off by default, allowing the flag so external users can add/inject dynamic linking support seems acceptable.

Misc/NEWS.d/next/Build/2025-12-03-10-44-42.gh-issue-142234.i1kaFb.rst

diff --git a/Misc/NEWS.d/next/Build/2025-12-03-10-44-42.gh-issue-142234.i1kaFb.rst b/Misc/NEWS.d/next/Build/2025-12-03-10-44-42.gh-issue-142234.i1kaFb.rst
new file mode 100644
index 0000000..a586512
--- /dev/null
+++ b/Misc/NEWS.d/next/Build/2025-12-03-10-44-42.gh-issue-142234.i1kaFb.rst
@@ -0,0 +1,3 @@
+Allow ``--enable-wasm-dynamic-linking`` for WASI. While CPython doesn't
+directly support it so external/downstream users do not have to patch in
+support for the flag.

configure

diff --git a/configure b/configure
index 1561f7f..7561fb9 100755
--- a/configure
+++ b/configure
@@ -1824,7 +1824,8 @@
                           no)
   --enable-wasm-dynamic-linking
                           Enable dynamic linking support for WebAssembly
-                          (default is no)
+                          (default is no); WASI requires an external dynamic
+                          loader to handle imports
   --enable-wasm-pthreads  Enable pthread emulation for WebAssembly (default is
                           no)
   --enable-shared         enable building a shared Python library (default is
@@ -7415,7 +7416,7 @@
   Emscripten) :
      ;; #(
   WASI) :
-    as_fn_error $? "WASI dynamic linking is not implemented yet." "$LINENO" 5 ;; #(
+     ;; #(
   *) :
     as_fn_error $? "--enable-wasm-dynamic-linking only applies to Emscripten and WASI" "$LINENO" 5
    ;;

configure.ac

diff --git a/configure.ac b/configure.ac
index f2a7319..fa24bc7 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1323,11 +1323,11 @@
 AC_MSG_CHECKING([for --enable-wasm-dynamic-linking])
 AC_ARG_ENABLE([wasm-dynamic-linking],
   [AS_HELP_STRING([--enable-wasm-dynamic-linking],
-                  [Enable dynamic linking support for WebAssembly (default is no)])],
+                  [Enable dynamic linking support for WebAssembly (default is no); WASI requires an external dynamic loader to handle imports])],
 [
   AS_CASE([$ac_sys_system],
     [Emscripten], [],
-    [WASI], [AC_MSG_ERROR([WASI dynamic linking is not implemented yet.])],
+    [WASI], [],
     [AC_MSG_ERROR([--enable-wasm-dynamic-linking only applies to Emscripten and WASI])]
   )
 ], [