[pytorch][nnc] update external functions for mobile build (#56850)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56850
This is part of the changes to enable NNC AOT compilation for mobile.
The generated kernels need to call these external functions thus change the declarations to use C linkage when building the mobile runtime.
Added nnc_aten_addmm external function.
ghstack-source-id: 127877411
Test Plan:
- build & CI;
- tested mobile build with stacked PRs;
Reviewed By: ZolotukhinM
Differential Revision: D27897154
fbshipit-source-id: 61d5499d7781a83bd2657859659fd1b5043d6b04
