patch 9.0.1166: code is indented more than necessary

Problem:    Code is indented more than necessary.
Solution:   Use an early return where it makes sense. (Yegappan Lakshmanan,
            closes #11792)
diff --git a/src/ex_getln.c b/src/ex_getln.c
index 49331c4..2407bce 100644
--- a/src/ex_getln.c
+++ b/src/ex_getln.c
@@ -4146,16 +4146,16 @@
 	return NULL;
 
     p = get_ccline_ptr();
-    if (p != NULL && p->xpc != NULL)
-    {
-	char_u *cmd_compl;
+    if (p == NULL || p->xpc == NULL)
+	return NULL;
 
-	set_expand_context(p->xpc);
+    char_u *cmd_compl;
 
-	cmd_compl = cmdcomplete_type_to_str(p->xpc->xp_context);
-	if (cmd_compl != NULL)
-	    return vim_strsave(cmd_compl);
-    }
+    set_expand_context(p->xpc);
+
+    cmd_compl = cmdcomplete_type_to_str(p->xpc->xp_context);
+    if (cmd_compl != NULL)
+	return vim_strsave(cmd_compl);
 
     return NULL;
 }