Fix broken visibility for symbols declared by DEFINE_AEABI_FUNCTION_ALIAS().

[mmel]

Summary

EFINE_AEABI_FUNCTION_ALIAS() macro uses '.set' directive for
declaration of aliased symbol. Unfortunately, '.set' doesn't
inherit visibility of base symbol, and macro don’t explicitly
sets visibility for aliased one.

Note: DEFINE_AEABI_FUNCTION_ALIAS() is used only for ARM,
so this change doesn't affect other architectures.

MFC after: 2 months

[andrew]

This should be sent upstream

[dim]

This is already done upstream slightly differently: https://reviews.llvm.org/rL285478

I will just import that revision instead. Since it is from upstream, I see no harm in MFC'ing it after 3 days.

[mmel]

Please, do not do it.
This must be MFCed together with r313866 or we broke all packages.
And I want little more time to be sure that r313866 is OK.

[dim]

In D9633#199282, @meloun-miracle-cz wrote:

Please, do not do it.
This must be MFCed together with r313866 or we broke all packages.
And I want little more time to be sure that r313866 is OK.

Sure, just ping me when you need it MFC'd, or you can do it yourself if you like.