enable WAMR_BUILD_WASI_EPHEMERAL_NN by default (#4381)

cf. https://github.com/bytecodealliance/wasm-micro-runtime/issues/4326

build-scripts/config_common.cmake

@@ -539,6 +539,9 @@ if (WAMR_BUILD_WASI_NN EQUAL 1)
   if (DEFINED WAMR_BUILD_WASI_NN_EXTERNAL_DELEGATE_PATH)
       add_definitions (-DWASM_WASI_NN_EXTERNAL_DELEGATE_PATH="${WAMR_BUILD_WASI_NN_EXTERNAL_DELEGATE_PATH}")
   endif ()
+  if (NOT DEFINED WAMR_BUILD_WASI_EPHEMERAL_NN)
+      set(WAMR_BUILD_WASI_EPHEMERAL_NN 1)
+  endif()
   if (WAMR_BUILD_WASI_EPHEMERAL_NN EQUAL 1)
       message ("     WASI-NN: use 'wasi_ephemeral_nn' instead of 'wasi-nn'")
       add_definitions (-DWASM_ENABLE_WASI_EPHEMERAL_NN=1)

doc/build_wamr.md

@@ -113,7 +113,7 @@ cmake -DWAMR_BUILD_PLATFORM=linux -DWAMR_BUILD_TARGET=ARM
 - **WAMR_BUILD_WASI_NN_EXTERNAL_DELEGATE_PATH**=Path to the external delegate shared library (e.g. `libedgetpu.so.1.0` for Coral USB)
 
 ### **Enable lib wasi-nn with `wasi_ephemeral_nn` module support**
-- **WAMR_BUILD_WASI_EPHEMERAL_NN**=1/0, default to disable if not set
+- **WAMR_BUILD_WASI_EPHEMERAL_NN**=1/0, default to enable if not set
 
 ### **Disable boundary check with hardware trap**
 - **WAMR_DISABLE_HW_BOUND_CHECK**=1/0, default to enable if not set and supported by platform