Fix Indian time zone test when run by Irishmen (bug#45818)

* test/lisp/calendar/solar-tests.el (solar-sunrise-sunset):
Inhibit any attempt by confused calendar code to apply daylight saving
correction when Irish time zone settings are in effect.  It's not
entirely clear why this is needed but may be related to the fact that
'IST' stands for both Irish and Indian Standard Time, and that Ireland
uses reversed daylight saving in winter.

test/lisp/calendar/solar-tests.el

@@ -26,7 +26,9 @@
         (calendar-longitude 75.8)
         (calendar-time-zone +330)
         (calendar-standard-time-zone-name "IST")
-        (calendar-daylight-time-zone-name "IST")
+        ;; Make sure our clockwork isn't confused by daylight saving rules
+        ;; in effect for any other time zone (bug#45818).
+        (calendar-daylight-savings-starts nil)
         (epsilon (/ 60.0)))             ; Minute accuracy is good enough.
     (let* ((sunrise-sunset (solar-sunrise-sunset '(12 30 2020)))
            (sunrise (car (nth 0 sunrise-sunset)))