win: Provide strcasecmp() in <strings.h> in compat

compat/win/strings.cc

+// Copyright 2015 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include <strings.h>
+
+#include <string.h>
+
+extern "C" {
+
+int strcasecmp(const char* s1, const char* s2) {
+  return _stricmp(s1, s2);
+}
+
+}  // extern "C"