tools: fix undeclared identifier FALSE

PR-URL: #36276
Reviewed-By: Richard Lau <rlau@redhat.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>

tools/icu/iculslocs.cc

@@ -150,7 +150,7 @@ int localeExists(const char* loc, UBool* exists) {
   }
   icu::LocalUResourceBundlePointer aResource(
       ures_openDirect(packageName.data(), loc, &status));
-  *exists = FALSE;
+  *exists = false;
   if (U_SUCCESS(status)) {
     *exists = true;
     if (VERBOSE > 1) {