patch 9.1.1145: multi-line completion has wrong indentation for last line

Problem:  When expanding omni completion items with newlines (e.g.
          `then\n\t\nend`), the end statement gets wrong indentation.
Solution: Add OPENLINE_FORCE_INDENT flag to make open_line() use
          second_line_indent directly (glepnir)

closes: #16614

Signed-off-by: glepnir <glephunter@gmail.com>
Signed-off-by: Justin M. Keyes <justinkz@gmail.com>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/vim.h b/src/vim.h
index 2ebc8fe..da2835c 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -1175,12 +1175,13 @@
 #define INSCHAR_COM_LIST 16	// format comments with list/2nd line indent
 
 // flags for open_line()
-#define OPENLINE_DELSPACES  0x01    // delete spaces after cursor
-#define OPENLINE_DO_COM	    0x02    // format comments
-#define OPENLINE_KEEPTRAIL  0x04    // keep trailing spaces
-#define OPENLINE_MARKFIX    0x08    // fix mark positions
-#define OPENLINE_COM_LIST   0x10    // format comments with list/2nd line indent
-#define OPENLINE_FORMAT	    0x20    // formatting long comment
+#define OPENLINE_DELSPACES	0x01    // delete spaces after cursor
+#define OPENLINE_DO_COM		0x02    // format comments
+#define OPENLINE_KEEPTRAIL	0x04    // keep trailing spaces
+#define OPENLINE_MARKFIX	0x08    // fix mark positions
+#define OPENLINE_COM_LIST	0x10    // format comments with list/2nd line indent
+#define OPENLINE_FORMAT		0x20    // formatting long comment
+#define OPENLINE_FORCE_INDENT	0x40    // use second_line_indent without indent logic
 
 // There are five history tables:
 #define HIST_CMD	0	// colon commands