Ticket #2134: configure.ac: add support for AM_SILENT_RULES

Inspired by http://www.flameeyes.eu/autotools-mythbuster/automake/silent.html
Conditionally enabling AM_SILENT_RULES if supported

Signed-off-by: Sergei Trofimovich <slyfox@inbox.ru>

configure.ac

@@ -11,6 +11,9 @@ AC_CONFIG_AUX_DIR(config)
 MC_VERSION
 AM_INIT_AUTOMAKE(mc, ${VERSION} )
 
+dnl enable silent rules by default (if yet)
+m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
+
 AM_CONFIG_HEADER(config.h)
 AM_MAINTAINER_MODE
 AC_CANONICAL_HOST