core: add get_header_version()

gevent/core_.pyx

@@ -2,6 +2,7 @@ cimport libev
 
 
 __all__ = ['get_version',
+           'get_header_version',
            'supported_backends',
            'recommended_backends',
            'embeddable_backends',
@@ -78,6 +79,10 @@ def get_version():
     return 'libev-%d.%02d' % (libev.ev_version_major(), libev.ev_version_minor())
 
 
+def get_header_version():
+    return 'libev-%d.%02d' % (libev.EV_VERSION_MAJOR, libev.EV_VERSION_MINOR)
+
+
 # This list backends in the order they are actually tried by libev
 _flags = [(libev.EVBACKEND_PORT, 'port'),
           (libev.EVBACKEND_KQUEUE, 'kqueue'),