[libc++abi] is_strcmp parameter to is_equal is unused for WIN32

Summary: Mark it as unused to avoid -Wunused-parameter.

Reviewers: EricWF, srhines, mstorsjo

Subscribers: christof, ldionne, libcxx-commits, cfe-commits

Differential Revision: https://reviews.llvm.org/D52368

git-svn-id: https://llvm.org/svn/llvm-project/libcxxabi/trunk@342764 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/src/private_typeinfo.cpp b/src/private_typeinfo.cpp
index a0326a1..67a5a62 100644
--- a/src/private_typeinfo.cpp
+++ b/src/private_typeinfo.cpp
@@ -64,6 +64,7 @@
         return x == y;
     return strcmp(x->name(), y->name()) == 0;
 #else
+    (void) use_strcmp;
     return (x == y) || (strcmp(x->name(), y->name()) == 0);
 #endif
 }