bug#21816: elisp-mode-tests fails on a case-preserving filesystem

[Eli Zaretskii]

> From: Juanma Barranquero <lekktu@gmail.com>
> Date: Tue, 3 Nov 2015 02:19:54 +0100
> Cc: 21816@debbugs.gnu.org, Stephen Leake <stephen_leake@stephe-leake.org>
> 
> An additional complication is that file-equal-p is intended to compare 
> existing
> files ("If FILE1 or FILE2 does not exist, the return value is unspecified."),
> but the xref-elisp-location values do not seem to be so constrained.

We could introduce a new function, file-name-equal-p, say, that would
be free of this limitation (for the price of not being able to compare
a file name with its 8+3 short variant and such likes).