src: fix inconsistency in extern declaration

NodeCounterProvider is declared as extern but defined as EXTERN_C.
This confuses clang-cl.

PR-URL: #20436
Refs: #19630
Reviewed-By: Tiancheng "Timothy" Gu <timothygu99@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Refael Ackermann <refack@gmail.com>
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

src/node_win32_perfctr_provider.cc

@@ -119,7 +119,7 @@ PPERF_COUNTERSET_INSTANCE perfctr_instance;
 namespace node {
 
 
-EXTERN_C DECLSPEC_SELECTANY HANDLE NodeCounterProvider = nullptr;
+HANDLE NodeCounterProvider = nullptr;
 
 void InitPerfCountersWin32() {
   ULONG status;