S390: Override QEMU_CAPS_NO_ACPI for s390x

Starting a KVM guest on s390 fails immediately. This is because
"qemu --help" reports -no-acpi even for the s390(x) architecture but
-no-acpi isn't supported there.
Workaround is to remove QEMU_CAPS_NO_ACPI from the capability set
after the version/capability extraction.

Signed-off-by: Viktor Mihajlovski <mihajlov@linux.vnet.ibm.com>
(cherry picked from commit 6a6c347118)

(crobinso: add Viktor to AUTHORS)

AUTHORS

@@ -237,6 +237,7 @@ Patches have also been contributed by:
   Beat Jörg            <Beat.Joerg@ssatr.ch>
   Gao feng             <gaofeng@cn.fujitsu.com>
   Dipankar Sarma       <dipankar@in.ibm.com>
+  Viktor Mihajlovski   <mihajlov@linux.vnet.ibm.com>
 
   [....send patches to get your name here....]
 

src/qemu/qemu_capabilities.c

@@ -1496,6 +1496,11 @@ int qemuCapsExtractVersionInfo(const char *qemu, const char *arch,
         qemuCapsSet(flags, QEMU_CAPS_PCI_MULTIBUS);
     }
 
+    /* S390 and probably other archs do not support no-acpi -
+       maybe the qemu option parsing should be re-thought. */
+    if (STRPREFIX(arch, "s390"))
+        qemuCapsClear(flags, QEMU_CAPS_NO_ACPI);
+
     /* qemuCapsExtractDeviceStr will only set additional flags if qemu
      * understands the 0.13.0+ notion of "-device driver,".  */
     if (qemuCapsGet(flags, QEMU_CAPS_DEVICE) &&