Removing double entry of 'udm_http.h' in Makefile

--- ./include/Makefile.am
+++ ./include/Makefile.am
@@ -21,7 +21,6 @@ udm_xmalloc.h \
 udm_id3.h \
 udm_http.h \
 udm_crc32.h \
-udm_http.h \
 udm_boolean.h \
 udm_server.h \
 udm_searchtool.h \