Allow s2n_strerror_debug output without unecessary filepath prefixed

[raycoll]

Problem:

s2n_strerror_debug returns a debug string that contains a line number in s2n where the error occurred. This line number can contain excessive file path information that results in a string that is longer than necessary to debug information in s2n. For example: Error encountered in /not/useful/file/path/prefix/for/the/error/tls/s2n_recv.c:53

The file path information can create larger log lines than necessary.

Solution:

Allow a build or runtime switch to only write the s2n source file name and line number. The path information is not necessary, assuming s2n does not repeat file names in source code.

• Does this change what S2N sends over the wire? No
• Does this change any public APIs? Maybe
• Which versions of TLS will this impact? N/A

Requirements / Acceptance Criteria:

Solution must have an option the user can set during build or runtime to get a s2n_strerror_debug output that does not have extra file path prefixes in it.