intel/error2aub: strenghten batchbuffer identifier marker

Found out that some base64 data matched the '---' identifier. We can
avoid this by adding the surrounding spaces.

Signed-off-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
Reviewed-by: Rafael Antognolli <rafael.antognolli@intel.com>

src/intel/tools/error2aub.c

@@ -339,9 +339,9 @@ main(int argc, char *argv[])
          continue;
       }
 
-      char *dashes = strstr(line, "---");
+      char *dashes = strstr(line, " --- ");
       if (dashes) {
-         dashes += 4;
+         dashes += 5;
 
          engine_from_name(line, &active_engine_class, &active_engine_instance);