Use AM_MAINTAINER_MODE([enable])

Use better default, but allow configure flag to remain.

Author: Konstanty

configure.ac

@@ -9,7 +9,7 @@ AM_INIT_AUTOMAKE
 m4_ifdef([AM_SILENT_RULES], [AM_SILENT_RULES])
 AC_CONFIG_HEADERS([src/config.h])
 AC_CONFIG_MACRO_DIR([m4])
-AM_MAINTAINER_MODE
+AM_MAINTAINER_MODE([enable])
 
 dnl Checks for programs.
 dnl I am disabling static libraries here because otherwise libtool insists on