Add missing config symbol when building uml on amd64 hosts, it would keep asking for host machine type

SVN-Revision: 13166

target/linux/uml/config/x86_64

@@ -54,6 +54,7 @@ CONFIG_LEGACY_PTY_COUNT=256
 # CONFIG_MAC_PARTITION is not set
 CONFIG_MAGIC_SYSRQ=y
 CONFIG_MCONSOLE=y
+CONFIG_MCORE2=y
 # CONFIG_MINI_FO is not set
 # CONFIG_MMAPPER is not set
 CONFIG_MK8=y