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

compat/win/strings.h

+// 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.
+
+#ifndef CRASHPAD_COMPAT_WIN_STRINGS_H_
+#define CRASHPAD_COMPAT_WIN_STRINGS_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+int strcasecmp(const char* s1, const char* s2);
+
+#ifdef __cplusplus
+}  // extern "C"
+#endif
+
+#endif  // CRASHPAD_COMPAT_WIN_STRINGS_H_