util: don't dump /proc/cpuinfo contents in debug info

This is hardly useful, it's trivial for developers to get that info by running
cat /proc/cpuinfo.

Fixes #3155

src/basic/virt.c

@@ -280,7 +280,7 @@ static int detect_vm_uml(void) {
                 return VIRTUALIZATION_UML;
         }
 
-        log_debug("No virtualization found in /proc/cpuinfo (%s)", cpuinfo_contents);
+        log_debug("No virtualization found in /proc/cpuinfo.");
         return VIRTUALIZATION_NONE;
 }