Fix signature mismatch in standalone.c. NFC

See #18285

system/lib/standalone/standalone.c

@@ -19,6 +19,7 @@
 
 #include <emscripten.h>
 #include <emscripten/heap.h>
+#include <emscripten/console.h>
 #include <wasi/api.h>
 #include <wasi/wasi-helpers.h>
 
@@ -208,7 +209,7 @@ imported__wasi_fd_write(__wasi_fd_t fd,
                         __wasi_size_t* nwritten);
 
 // Write a buffer + a newline.
-static void wasi_writeln(__wasi_fd_t fd, char* buffer) {
+static void wasi_writeln(__wasi_fd_t fd, const char* buffer) {
   struct __wasi_ciovec_t iovs[2];
   iovs[0].buf = (uint8_t*)buffer;
   iovs[0].buf_len = strlen(buffer);
@@ -218,9 +219,9 @@ static void wasi_writeln(__wasi_fd_t fd, char* buffer) {
   imported__wasi_fd_write(fd, iovs, 2, &nwritten);
 }
 
-void _emscripten_out(char* text) { wasi_writeln(1, text); }
+void _emscripten_out(const char* text) { wasi_writeln(1, text); }
 
-void _emscripten_err(char* text) { wasi_writeln(2, text); }
+void _emscripten_err(const char* text) { wasi_writeln(2, text); }
 
 // In the non-standalone build we define this helper function in JS to avoid
 // signture mismatch issues.