- acinclude.m4: fix exec_prefix variable in cdk-mode too

Signed-off-by: Thilo Graf <dbt@novatux.de>

acinclude.m4

@@ -161,9 +161,6 @@ if test "$TARGET" = "native"; then
 	if test "$prefix" = "NONE"; then
 		prefix=/usr/local
 	fi
-	if test "$exec_prefix" = "NONE"; then
-		exec_prefix=$prefix
-	fi
 	targetprefix=$prefix
 	TARGET_PREFIX=$prefix
 	AC_DEFINE_UNQUOTED(TARGET_PREFIX, "$TARGET_PREFIX", [The targets prefix])
@@ -191,6 +188,10 @@ else
 	AC_MSG_ERROR([invalid target $TARGET, choose on from native,cdk]);
 fi
 
+if test "$exec_prefix" = "NONE"; then
+	exec_prefix=$prefix
+fi
+
 AC_CANONICAL_BUILD
 AC_CANONICAL_HOST
 AC_SYS_LARGEFILE