qemu-ga: fixes for win32 build of qemu-ga

Various stubs and #ifdefs to compile for Windows using mingw
cross-build. Still has 1 linker error due to a dependency on the
forthcoming win32 versions of the GAChannel/transport class.

qga/commands-win32.c

@@ -0,0 +1,91 @@
+/*
+ * QEMU Guest Agent win32-specific command implementations
+ *
+ * Copyright IBM Corp. 2012
+ *
+ * Authors:
+ *  Michael Roth      <mdroth@linux.vnet.ibm.com>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or later.
+ * See the COPYING file in the top-level directory.
+ */
+
+#include <glib.h>
+#include "qga/guest-agent-core.h"
+#include "qga-qmp-commands.h"
+#include "qerror.h"
+
+void qmp_guest_shutdown(bool has_mode, const char *mode, Error **err)
+{
+    error_set(err, QERR_UNSUPPORTED);
+}
+
+int64_t qmp_guest_file_open(const char *path, bool has_mode, const char *mode, Error **err)
+{
+    error_set(err, QERR_UNSUPPORTED);
+    return 0;
+}
+
+void qmp_guest_file_close(int64_t handle, Error **err)
+{
+    error_set(err, QERR_UNSUPPORTED);
+}
+
+GuestFileRead *qmp_guest_file_read(int64_t handle, bool has_count,
+                                   int64_t count, Error **err)
+{
+    error_set(err, QERR_UNSUPPORTED);
+    return 0;
+}
+
+GuestFileWrite *qmp_guest_file_write(int64_t handle, const char *buf_b64,
+                                     bool has_count, int64_t count, Error **err)
+{
+    error_set(err, QERR_UNSUPPORTED);
+    return 0;
+}
+
+GuestFileSeek *qmp_guest_file_seek(int64_t handle, int64_t offset,
+                                   int64_t whence, Error **err)
+{
+    error_set(err, QERR_UNSUPPORTED);
+    return 0;
+}
+
+void qmp_guest_file_flush(int64_t handle, Error **err)
+{
+    error_set(err, QERR_UNSUPPORTED);
+}
+
+/*
+ * Return status of freeze/thaw
+ */
+GuestFsfreezeStatus qmp_guest_fsfreeze_status(Error **err)
+{
+    error_set(err, QERR_UNSUPPORTED);
+    return 0;
+}
+
+/*
+ * Walk list of mounted file systems in the guest, and freeze the ones which
+ * are real local file systems.
+ */
+int64_t qmp_guest_fsfreeze_freeze(Error **err)
+{
+    error_set(err, QERR_UNSUPPORTED);
+    return 0;
+}
+
+/*
+ * Walk list of frozen file systems in the guest, and thaw them.
+ */
+int64_t qmp_guest_fsfreeze_thaw(Error **err)
+{
+    error_set(err, QERR_UNSUPPORTED);
+    return 0;
+}
+
+/* register init/cleanup routines for stateful command groups */
+void ga_command_state_init(GAState *s, GACommandState *cs)
+{
+}