[PATCH xserver] Workaround a sdksyms problem with gcc5 on Cygwin

[Adam Jackson]

On Mon, 2017-03-06 at 17:44 +0000, Jon Turney wrote:
> The linemarkers in the preprocessor output from gcc5 on Cygwin have
> canonicalized paths to included files (e.g. xserver/build/../include/misc.h
> is canonicalized to xserver/build/include/misc.h). (see gcc svn rev 210264,
> which causes the transformation performed by -fcanonical-system-headers to
> be applied to all include pathnames)
> 
> These canonicalized paths won't match $topdir, so sdksyms doesn't look at
> the contents of those headers for sdk exported symbols.
> 
> Workaround this by canonicalizing all the paths we consider, using readlink.
> 
> v2:
> Keep a cache of readlink results so it isn't quite so dreadfully slow.

remote: I: patch #142416 updated using rev bca221609004aecbcc8928382ad29ce319d2eb6f.
remote: I: 1 patch(es) updated to state Accepted.
To ssh://git.freedesktop.org/git/xorg/xserver
   ac15d4c..bca2216  master -> master

- ajax