PHPC-2195: Use less ambiguous path in mongocrypt.h compat include (#1407)

Add an ifndef block so we're not just relying on the actual mongocrypt.h include.

Add copyright headers to libmongocrypt-compat headers.

Author: jmikola

src/libmongocrypt-compat/mongocrypt-export.h

@@ -1,3 +1,19 @@
+/*
+ * Copyright 2020-present MongoDB, Inc.
+ *
+ * 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 MONGOCRYPT_EXPORT_H
 #define MONGOCRYPT_EXPORT_H
 

src/libmongocrypt-compat/mongocrypt/mongocrypt.h

@@ -1 +1,28 @@
-#include "../libmongocrypt/src/mongocrypt.h"
+/*
+ * Copyright 2020-present MongoDB, Inc.
+ *
+ * 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 PHONGO_COMPAT_MONGOCRYPT_H
+#define PHONGO_COMPAT_MONGOCRYPT_H
+
+/* This header forwards includes for "mongocrypt/mongocrypt.h" to the desired
+ * header in the bundled libmongocrypt submodule. This is used when compiling
+ * bundled versions of libmongoc and libmongocrypt and is necessary because
+ * libmongocrypt's source directory is not named "mongocrypt/".
+ *
+ * This path is relative to the PHPC project directory to avoid ambiguity. */
+#include "src/libmongocrypt/src/mongocrypt.h"
+
+#endif /* PHONGO_COMPAT_MONGOCRYPT_H */