Adding "build_options" to bpy.app, a frozenset containing strings matching optional feature's build defines (like 'FFMPEG', 'MOD_BOOLEAN', 'INTERNATIONAL', etc.) for all enabled elements.

Note I tried to select all interesting defines, but this might be extended if needed...

source/blender/python/intern/bpy_app_build_options.h

@@ -0,0 +1,32 @@
+/*
+ * ***** BEGIN GPL LICENSE BLOCK *****
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Contributor(s): Bastien Montagne
+ *
+ * ***** END GPL LICENSE BLOCK *****
+ */
+
+/** \file blender/python/intern/bpy_app_build_options.h
+ *  \ingroup pythonintern
+ */
+
+#ifndef __BPY_APP_BUILD_OPTIONS_H__
+#define __BPY_APP_BUILD_OPTIONS_H__
+
+PyObject *BPY_app_build_options_struct(void);
+
+#endif  /* __BPY_APP_BUILD_OPTIONS_H__ */