patch 8.2.3780: ":cd" works differently on MS-Windows

Problem:    ":cd" works differently on MS-Windows.
Solution:   Add the 'cdhome' option. (closes #9324)
diff --git a/src/optiondefs.h b/src/optiondefs.h
index 6a96a9f..c392442 100644
--- a/src/optiondefs.h
+++ b/src/optiondefs.h
@@ -549,6 +549,10 @@
 			    (char_u *)&p_cmp, PV_NONE,
 			    {(char_u *)"internal,keepascii", (char_u *)0L}
 			    SCTX_INIT},
+    {"cdhome",	    "cdh",  P_BOOL|P_VI_DEF|P_VIM|P_SECURE,
+			    (char_u *)&p_cdh, PV_NONE,
+			    {(char_u *)FALSE, (char_u *)0L}
+			    SCTX_INIT},
     {"cdpath",	    "cd",   P_STRING|P_EXPAND|P_VI_DEF|P_SECURE|P_COMMA|P_NODUP,
 #ifdef FEAT_SEARCHPATH
 			    (char_u *)&p_cdpath, PV_NONE,