[Web] Remove unnecessary EMCC_FORCE_STDLIBS in dlink builds

As discussed with upstream, the C/C++ standard library is always fully
included when building with MAIN_MODULE=1, so using EMCC_FORCE_STDLIBS
is not necessary in our case.

platform/web/SCsub

@@ -71,8 +71,6 @@ if env["dlink_enabled"]:
     sys_env.Append(LINKFLAGS=["-s", "MAIN_MODULE=1"])
     sys_env.Append(LINKFLAGS=["-s", "EXPORT_ALL=1"])
     sys_env.Append(LINKFLAGS=["-s", "WARN_ON_UNDEFINED_SYMBOLS=0"])
-    # Force exporting the standard library (printf, malloc, etc.)
-    sys_env["ENV"]["EMCC_FORCE_STDLIBS"] = "libc,libc++,libc++abi"
     sys_env["CCFLAGS"].remove("-fvisibility=hidden")
     sys_env["LINKFLAGS"].remove("-fvisibility=hidden")