Added Irish Summer Time.

dlls/ntdll/time.c

diff --git a/dlls/ntdll/time.c b/dlls/ntdll/time.c
index 3321af0..75bd513 100644
--- a/dlls/ntdll/time.c
+++ b/dlls/ntdll/time.c
@@ -176,6 +176,9 @@
    {"BST",
     {'G','M','T',' ','S','t','a','n','d','a','r','d',' ','T','i','m','e','\0'},
     -60, 1},
+   {"IST",
+    {'I','r','i','s','h',' ','S','u','m','m','e','r',' ','T','i','m','e','\0'},
+    -60, 1},
    {"GMT",
     {'G','M','T',' ','S','t','a','n','d','a','r','d',' ','T','i','m','e','\0'},
     0, 0},