> I mean removing the -m part from your line, not specifying each file individually.

-m is needed. Files built under pnacl (pnacl translator) are by default  with executable permission, thus the generating debuginfo phase will try to strip them and cause error. The reason is those files are compiled by NaCl toochain(modified gcc toolchain). 

So I change those files without executable permission. This is aligned with the permission how Google Chrome pnacl translators, you could check ~/.config/google-chrome/pnacl/.