sstate: Update mtime/atime for sig/siginfo files in sstate_checkhashes()

If we touch sstatefile, we should also touch any .sig/.siginfo file if we can.
We try and keep them both updated with accesses so one isn't removed without
the other and they stay consistent.

[YOCTO #15289]

(From OE-Core rev: 2bd595a9d95fac64174a25759124a0aa3d0dd001)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit cc07895f951140dbbffcf32d3eabf65788cc4d00)
Signed-off-by: Yoann Congal <yoann.congal@smile.fr>
Signed-off-by: Paul Barker <paul@pbarker.dev>

meta/classes-global/sstate.bbclass

@@ -978,6 +978,9 @@ def sstate_checkhashes(sq_data, d, siginfo=False, currentcount=0, summary=True,
 
         if os.path.exists(sstatefile):
             oe.utils.touch(sstatefile)
+            for ext in ['.sig', '.siginfo']:
+                if os.path.exists(sstatefile + ext):
+                    oe.utils.touch(sstatefile + ext)
             found.add(tid)
             bb.debug(2, "SState: Found valid sstate file %s" % sstatefile)
         else: