[libc] Add LLVM libc specific functions to llvm_libc_ext.td.

[michaelrj]

Summary

Also moved most of the common type definitions from libc/spec/stdc.td
to libc/spec/spec.td so that they can be used to list functions in llvm_libc_ext.td.

[sivachandra]

For all libc changes, the commit message should have [libc] prefixed to the first line.

libc/spec/stdc.td

4

Can you point to the line in public_api.td which has the definitions for FILE related types.

[michaelrj]

Minor formatting fixes.

Update commit message.
Fix comment in libc/spec/stdc.td.

libc/spec/stdc.td

4

oops, that should say libc/config/[platform]/api.td, and the line is 30: https://github.com/llvm/llvm-project/blob/master/libc/config/linux/api.td#L30. The comment is now updated to reflect that.

[sivachandra]

libc/spec/stdc.td

4

Ah! Just remove the comment from here may be. Its more confusing than actually explaining the code.

[sivachandra]

Please note that I have updated the commit message. Depending on how you land this patch, you might have to update the commit message in your local repo as well.

[michaelrj]

fix commit message locally

[michaelrj]

remove unnecessary comment