Fix initial value of dynCalls (#22422)

This was a mistake from #22418.

See
#22418 (comment)

Author: sbc100

src/library.js

@@ -1857,7 +1857,7 @@ addToLibrary({
 
 #if DYNCALLS || !WASM_BIGINT
 #if MINIMAL_RUNTIME
-  $dynCalls: '[]',
+  $dynCalls: '{}',
 #endif
   $dynCallLegacy__deps: [
 #if MAIN_MODULE == 1

test/code_size/embind_hello_wasm.json

@@ -2,9 +2,9 @@
   "a.html": 552,
   "a.html.gz": 380,
   "a.js": 9961,
-  "a.js.gz": 4352,
+  "a.js.gz": 4350,
   "a.wasm": 7820,
   "a.wasm.gz": 3526,
   "total": 18333,
-  "total_gz": 8258
+  "total_gz": 8256
 }