patch 9.1.0651: ex: trailing dot is optional for :g and :insert/:append

Problem:  ex: trailing dot is optional for :g and :insert/:append
Solution: don't break out early, when the next command is empty.
          (Mohamed Akram)

The terminating period is optional for the last command in a global
command list.

closes: #15407

Signed-off-by: Mohamed Akram <mohd.akram@outlook.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/ex_cmds.c b/src/ex_cmds.c
index c365937..4793737 100644
--- a/src/ex_cmds.c
+++ b/src/ex_cmds.c
@@ -3370,7 +3370,7 @@
 	{
 	    // No getline() function, use the lines that follow. This ends
 	    // when there is no more.
-	    if (eap->nextcmd == NULL || *eap->nextcmd == NUL)
+	    if (eap->nextcmd == NULL)
 		break;
 	    p = vim_strchr(eap->nextcmd, NL);
 	    if (p == NULL)
@@ -3378,6 +3378,8 @@
 	    theline = vim_strnsave(eap->nextcmd, p - eap->nextcmd);
 	    if (*p != NUL)
 		++p;
+	    else
+		p = NULL;
 	    eap->nextcmd = p;
 	}
 	else