girepository: Add version macros and functions. Fixes #200

This adds the following macros and functions: GI_MAJOR_VERSION, GI_MICRO_VERSION,
GI_MINOR_VERSION, GI_CHECK_VERSION, gi_get_major_version,gi_get_micro_version,
gi_get_minor_version.

Since we share a prefix with glib we have to namespace these by using the gi_
prefix. g_gi would also work but we already export symbols with gi_ like
gi_cclosure_marshal_generic(), gi_type_tag_get_ffi_type() and
gi_type_info_extract_ffi_return_value(), so let's not add another naming scheme.

giversion.c

@@ -0,0 +1,114 @@
+/* Copyright (C) 2018 Christoph Reiter
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the
+ * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ */
+
+#include "config.h"
+
+#include <girepository.h>
+
+/**
+ * SECTION:giversion
+ * @Title: Version Information
+ * @Short_description: macros and functions to check the girepository version
+ */
+
+/**
+ * GI_MAJOR_VERSION:
+ *
+ * The major version number of the girepository library.
+ *
+ * Since: 1.60
+ */
+
+/**
+ * GI_MINOR_VERSION:
+ *
+ * The minor version number of the girepository library.
+ *
+ * Since: 1.60
+ */
+
+/**
+ * GI_MICRO_VERSION:
+ *
+ * The micro version number of the girepository library.
+ *
+ * Since: 1.60
+ */
+
+/**
+ * GI_CHECK_VERSION:
+ * @major: the major version to check for
+ * @minor: the minor version to check for
+ * @micro: the micro version to check for
+ *
+ * Checks the version of the girepository library that is being compiled
+ * against.
+ *
+ * Returns: %TRUE if the version of the girepository header files
+ * is the same as or newer than the passed-in version.
+ *
+ * Since: 1.60
+ */
+
+/**
+ * gi_get_major_version:
+ *
+ * Returns the major version number of the girepository library.
+ * (e.g. in version 1.58.2 this is 1.)
+ *
+ * Returns: the major version number of the girepository library
+ *
+ * Since: 1.60
+ */
+guint
+gi_get_major_version (void)
+{
+  return GI_MAJOR_VERSION;
+}
+
+/**
+ * gi_get_minor_version:
+ *
+ * Returns the minor version number of the girepository library.
+ * (e.g. in version 1.58.2 this is 58.)
+ *
+ * Returns: the minor version number of the girepository library
+ *
+ * Since: 1.60
+ */
+guint
+gi_get_minor_version (void)
+{
+  return GI_MINOR_VERSION;
+}
+
+/**
+ * gi_get_micro_version:
+ *
+ * Returns the micro version number of the girepository library.
+ * (e.g. in version 1.58.2 this is 2.)
+ *
+ * Returns: the micro version number of the girepository library
+ *
+ * Since: 1.60
+ */
+guint
+gi_get_micro_version (void)
+{
+  return GI_MICRO_VERSION;
+}