[openssl-dev] System openssl header files are used when building openssl itself

[Salz, Rich]

> No, it doesn't. And it should not, right? As there is no folder openssl which
> has files like ssl.h.

In master, there should be include/openssl/ssl.h 

> But I did notice some files, like ssl_locl.h, are included in C files using
> "ssl_locl.h", instead of <openssl/ssl_locl.h>, already.

The file ssl_locl.h is local to the ssl directory.  It's a private implementation file, not used by outside of that directory.