Remove unused function in emscripten.py. NFC (#19841)

Loosk like its usage was removed in #11972.

Author: sbc100

emscripten.py

@@ -239,15 +239,6 @@ def report_missing_symbols(js_symbols):
     exit_with_error('entry symbol not defined (pass --no-entry to suppress): main')
 
 
-def proxy_debug_print(sync):
-  if settings.PTHREADS_DEBUG:
-    if sync:
-      return 'warnOnce("sync proxying function " + code);'
-    else:
-      return 'warnOnce("async proxying function " + code);'
-  return ''
-
-
 # Test if the parentheses at body[openIdx] and body[closeIdx] are a match to
 # each other.
 def parentheses_match(body, openIdx, closeIdx):