AM_SILENT_RULES([yes]) with backwards-compatiblity

Supported since automake-1.11. There is no point in having the very
verbose compile stuff running about, which cannot even silenced properly
with `make -s` by default. Otherwise, `make V=1` or
`--disable-silent-rules` are your friends

configure.ac

@@ -8,6 +8,8 @@ AC_CANONICAL_HOST
 AC_CANONICAL_TARGET
 
 AM_INIT_AUTOMAKE()
+m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
+
 AC_USE_SYSTEM_EXTENSIONS
 
 LT_PREREQ([2.2.6])