xenpm: Initialize cputopo pointer

Commit 250f0b43af ("libxl/libxc: Move libxl_get_cpu_topology()'s
hypercall buffer management to libxc") broke non-debug compilation:
on error path we may have uninitialized cputopo pointer.

Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Reported-by: Olaf Hering <olaf@aepfle.de>
Acked-by: Wei Liu <wei.liu2@citrix.com>
Acked-by: Ian Campbell <ian.campbell@citrix.com>

tools/misc/xenpm.c

@@ -355,7 +355,7 @@ static void signal_int_handler(int signo)
     int i, j, k;
     struct timeval tv;
     int cx_cap = 0, px_cap = 0;
-    xc_cputopo_t *cputopo;
+    xc_cputopo_t *cputopo = NULL;
     unsigned max_cpus;
 
     if ( xc_cputopoinfo(xc_handle, &max_cpus, NULL) != 0 )
@@ -960,7 +960,7 @@ void scaling_governor_func(int argc, char *argv[])
 
 void cpu_topology_func(int argc, char *argv[])
 {
-    xc_cputopo_t *cputopo;
+    xc_cputopo_t *cputopo = NULL;
     unsigned max_cpus;
     int i, rc;