libmemif: Add memif_cancel_poll_event() + bug fixing.

Change-Id: I27d6bf93216f1f639f01fad730506afdc7115e46
Signed-off-by: Milan Lenco <milan.lenco@pantheon.tech>
diff --git a/extras/libmemif/Makefile.am b/extras/libmemif/Makefile.am
index 1ff7e7e..82280a4 100644
--- a/extras/libmemif/Makefile.am
+++ b/extras/libmemif/Makefile.am
@@ -82,7 +82,7 @@
 
 check_PROGRAMS = unit_test
 
-include_HEADERS = src/libmemif.h
+include_HEADERS = src/libmemif.h src/memif.h
 
 lib_LTLIBRARIES = libmemif.la