Stop pretending to support extended-const proposal (#4258)

As far as I know, we don't implement the proposal at all.

```
spacetanuki% wasm2wat --enable-all data.28.wasm
(module
  (memory (;0;) 1)
  (data (;0;) (i32.const 42
    i32.const 0
    i32.sub) ""))
spacetanuki% toywasm --load data.28.wasm
spacetanuki% ~/git/wasm-micro-runtime/product-mini/platforms/darwin/b.classic/iwasm data.28.wasm
WASM module load failed: illegal opcode or constant expression required or type mismatch
spacetanuki%
```

data.28.wasm in the above example is a binary version of:
8d4f6aa2b0/test/core/data.wast (L184-L187)

build-scripts/config_common.cmake

@@ -677,7 +677,6 @@ endif ()
 message (
 "-- About Wasm Proposals:\n"
 "     Always-on:\n"
-"       \"Extended Constant Expressions\"\n"
 "       \"Multi-value\"\n"
 "       \"Non-trapping float-to-int conversions\"\n"
 "       \"Sign-extension operators\"\n"
@@ -698,6 +697,7 @@ message (
 "       \"Branch Hinting\"\n"
 "       \"Custom Annotation Syntax in the Text Format\"\n"
 "       \"Exception handling\"\n"
+"       \"Extended Constant Expressions\"\n"
 "       \"Import/Export of Mutable Globals\"\n"
 "       \"JS String Builtins\"\n"
 "       \"Relaxed SIMD\"\n"