Remove pointless 'qemuVersion' field from virQEMUDriverPtr

The QEMU driver struct has a 'qemuVersion' field that was previously
used to cache the version lookup from capabilities. With the recent
QEMU capabilities rewrite the caching happens at a lower level so
this field is pointless. Removing it avoids worries about locking
when updating it.
Signed-off-by: NDaniel P. Berrange <berrange@redhat.com>

src/qemu/qemu_conf.h

@@ -158,8 +158,6 @@ struct _virQEMUDriver {
 
     virThreadPoolPtr workerPool;
 
-    unsigned int qemuVersion;
-
     int nextvmid;
 
     virCgroupPtr cgroup;

src/qemu/qemu_driver.c

@@ -1501,14 +1501,15 @@ cleanup:
 static int qemuGetVersion(virConnectPtr conn, unsigned long *version) {
     virQEMUDriverPtr driver = conn->privateData;
     int ret = -1;
+    unsigned int qemuVersion;
 
     qemuDriverLock(driver);
     if (qemuCapsGetDefaultVersion(driver->caps,
                                   driver->capsCache,
-                                  &driver->qemuVersion) < 0)
+                                  &qemuVersion) < 0)
         goto cleanup;
 
-    *version = driver->qemuVersion;
+    *version = qemuVersion;
     ret = 0;
 
 cleanup: