target-i386: Support migratable=no properly

target-i386: Support migratable=no properly

When the "migratable" property was implemented, the behavior was tested
by changing the default on the code, but actually using the option on
the command-line (e.g. "-cpu host,migratable=false") doesn't work as
expected. This is a regression for a common use case of "-cpu host",
which is to enable features that are supported by the host CPU + kernel
before feature-specific code is added to QEMU.

Fix this by initializing the feature words for "-cpu host" on
x86_cpu_parse_featurestr(), right after parsing the CPU options.

Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Andreas Färber <afaerber@suse.de>
(cherry picked from commit 4d1b279b0675a8b483a5f101212d1dedfb1a3cec)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>