Enable silent build (can be overridden with 'make V=1') if the version of autotools being used is new enough.

configure.ac

@@ -11,6 +11,8 @@ AC_PREFIX_DEFAULT(/opt/libjpeg-turbo)
 # Always build with prototypes
 AC_DEFINE([HAVE_PROTOTYPES], 1, [Define if your compiler supports prototypes])
 
+m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES([yes])])
+
 # Checks for programs.
 SAVED_CFLAGS=${CFLAGS}
 SAVED_CPPFLAGS=${CPPFLAGS}