Only tweak the default prefix when run with --enable-maintainer-mode.

configure.ac

@@ -82,7 +82,9 @@ AM_CONFIG_HEADER([config.h])
 #
 # cH: hey, boys and girls, why do we do that?
 #
-AC_PREFIX_DEFAULT([`pwd`])
+if test "${USE_MAINTAINER_MODE}" = "yes"; then
+  AC_PREFIX_DEFAULT([`pwd`])
+fi
 
 AC_ARG_ENABLE([dim-of-world],
 [AC_HELP_STRING([--enable-dim-of-world="DIM1 ... DIMk"],