meson: add visibility argument

meson.build

@@ -17,6 +17,12 @@ conf_data.set('_DEFAULT_SOURCE', 1)
 
 cc = meson.get_compiler('c')
 
+# Add -fvisibility=hidden if compiler supports those
+add_project_arguments(
+    cc.get_supported_arguments('-fvisibility=hidden'),
+    language : ['c'])
+
+
 optional_arguments = [
   '-Wall',
   '-Wsign-compare',