[libxml2] Compile testapi with -Wno-unused-function

[Nick Wellnhofer <nwellnhof src gnome org>]

commit f404c4f500a0ec18b04463581d5d1b3aae7f7730
Author: Nick Wellnhofer <wellnhofer aevum de>
Date:   Tue Oct 31 17:14:43 2017 +0100

    Compile testapi with -Wno-unused-function

 Makefile.am |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index 748dfc2..15f78e1 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -191,6 +191,7 @@ testapi_SOURCES=testapi.c
 testapi_LDFLAGS = 
 testapi_DEPENDENCIES = $(DEPS)
 testapi_LDADD= $(LDADDS)
+testapi_CFLAGS = -Wno-unused-function
 
 runxmlconf_SOURCES=runxmlconf.c
 runxmlconf_LDFLAGS =