Xen: VIR_FROM_THIS cleanup

The virErrorDomain enum has VIR_FROM_XEN, VIR_FROM_XEND,
VIR_FROM_XENSTORE, VIR_FROM_SEXPR, and VIR_FROM_XENXM. Use
these elements in the corresponding .c files. While at it,
remove the VIR_FROM_THIS define in src/xenconfig/xenxs_private.h.

src/xen/xs_internal.c

@@ -52,7 +52,7 @@
 #include "xen_hypervisor.h"
 #include "virstring.h"
 
-#define VIR_FROM_THIS VIR_FROM_XEN
+#define VIR_FROM_THIS VIR_FROM_XENSTORE
 
 VIR_LOG_INIT("xen.xs_internal");
 

src/xenconfig/xen_common.c

@@ -39,6 +39,7 @@
 #include "virstring.h"
 #include "xen_common.h"
 
+#define VIR_FROM_THIS VIR_FROM_XEN
 
 /*
  * Convenience method to grab a long int from the config file object

src/xenconfig/xen_sxpr.c

@@ -41,6 +41,8 @@
 #include "virstoragefile.h"
 #include "virstring.h"
 
+#define VIR_FROM_THIS VIR_FROM_SEXPR
+
 VIR_LOG_INIT("xenconfig.xen_sxpr");
 
 /* Get a domain id from a S-expression string */

src/xenconfig/xen_xm.c

@@ -36,6 +36,7 @@
 #include "virstring.h"
 #include "xen_common.h"
 
+#define VIR_FROM_THIS VIR_FROM_XENXM
 
 static int
 xenParseXMOS(virConfPtr conf, virDomainDefPtr def)

src/xenconfig/xenxs_private.h

@@ -46,6 +46,4 @@
 #  define DEFAULT_VIF_SCRIPT "vif-bridge"
 # endif
 
-# define VIR_FROM_THIS VIR_FROM_NONE
-
 #endif /* __VIR_XENXS_PRIVATE_H__ */