libsysprof: sniff various forms of kernel process names

This is by no means perfect, but it gets the kernel tasks running on my
machine out of the profiles. We will no doubt need to add more in the
future, or find a way to record a flag for that in the capture format.

src/libsysprof/sysprof-process-info.c

@@ -51,6 +51,9 @@ sysprof_process_info_new (SysprofMountNamespace *mount_namespace,
                                                0, 0,
                                                SYSPROF_SYMBOL_KIND_PROCESS);
 
+  if (pid == 0)
+    self->fallback_symbol->is_kernel_process = TRUE;
+
   if (pid > 0)
     egg_bitset_add (self->thread_ids, pid);