Organized modules, added indirection for FFI vs extension loading (#10)

* mv src -> ext, lib -> src to be more in line with PHP module expectations

* Fixed dependency for ffi test

* Fixed path in format-check to C source

* CRT will now try the extension first, then FFI

ext/php_aws_crt.h

@@ -0,0 +1,39 @@
+
+#ifndef PHP_AWS_CRT_H
+#define PHP_AWS_CRT_H
+
+/**
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ * SPDX-License-Identifier: Apache-2.0.
+ */
+
+#ifdef HAVE_CONFIG_H
+#    include "config.h"
+#endif
+
+#include "php.h"
+
+#include "Zend/zend_extensions.h" /* for ZEND_EXTENSION_API_NO */
+
+#if ZEND_EXTENSION_API_NO < 220131226
+#    error "PHP >= 5.6 is required"
+#endif
+
+#define AWS_PHP_AT_LEAST_7 defined(ZEND_EXTENSION_API_NO_7_0_X) || (ZEND_EXTENSION_API_NO >= 320151012)
+
+ZEND_BEGIN_MODULE_GLOBALS(awscrt)
+long log_level;
+ZEND_END_MODULE_GLOBALS(awscrt)
+
+ZEND_EXTERN_MODULE_GLOBALS(awscrt)
+
+#define AWSCRT_GLOBAL(v) ZEND_MODULE_GLOBALS_ACCESSOR(awscrt, v)
+
+/* PHP 7 removed the string duplicate parameter */
+#if AWS_PHP_AT_LEAST_7
+#    define AWS_RETURN_STRING(s) RETURN_STRING(s)
+#else
+#    define AWS_RETURN_STRING(s) RETURN_STRING(s, 1)
+#endif
+
+#endif /* PHP_AWS_CRT_H */