Fix #44: Invert logic for disabled autoconf check

This patch not only fixes issue #44, it also refactores the --enable-xx
and --disable-yy logic by splitting the check and action into separate
blocks.  Slightly more readable.

Signed-off-by: Joachim Nilsson <[email protected]>

configure.ac

@@ -22,21 +22,11 @@ AC_PROG_INSTALL
 # The pidfile() code needs asprintf(), which relies on -D_GNU_SOURCE
 AC_GNU_SOURCE
 
-# Check if user even wants IPv6 support
-AC_ARG_ENABLE([ipv6],[AS_HELP_STRING([--disable-ipv6],
-	[disable IPv6 support, default: enabled])
-	],[
-	[ac_enable_ipv6="$enableval"],
-	[ac_enable_ipv6="yes"]
-])
-
-# Check if user wants to have build number encoded in binary
-AC_ARG_ENABLE([build-id],[AS_HELP_STRING([--enable-build-id@<:@=ID@:>@],
-	[enable build ID in 'smcroute -v', default: disabled])
-	],[
-	AS_IF([test "x$enableval" = "xyes" ], [build_id=`date +%y%m%d`], [build_id=$enableval])
-	AC_DEFINE_UNQUOTED([BUILD], "$build_id", [Build number, abbreviated date.])
-])
+# Check user options
+AC_ARG_ENABLE([build-id],
+	AS_HELP_STRING([--enable-build-id@<:@=ID@:>@], [enable build ID in 'smcroute -v', default: disabled]))
+AC_ARG_ENABLE([ipv6],
+	AS_HELP_STRING([--disable-ipv6], [disable IPv6 support, default: enabled]))
 
 # Checks for header files.
 AC_HEADER_STDC
@@ -64,8 +54,12 @@ AC_CHECK_SUN_LEN()
 AC_CHECK_MROUTE()
 
 # If IPv6 is enabled we must probe the system some more
-if test "x$ac_enable_ipv6" = "xyes"; then
-   AC_CHECK_MROUTE6()
-fi
+AS_IF([test "x$enable_ipv6" != "xno"],
+        AC_CHECK_MROUTE6())
+
+# Define BUILD in config.h, if enabled
+AS_IF([test "x$enable_build_id" = "xyes" ], [build_id=`date +%y%m%d`], [build_id=$enable_build_id],
+	AS_IF([test "x$build_id" != "xno" ],
+		AC_DEFINE_UNQUOTED([BUILD], "$build_id", [Build number, abbreviated date.])))
 
 AC_OUTPUT