patch 9.1.0915: GVim: default font size a bit too small

Problem:  GVim: default font size a bit too small
Solution: increase guifont size to 12 pt on GTK builds
          of gVim (matveyt).

fixes: #16172
closes: #16178

Signed-off-by: matveyt <matthewtarasov@yandex.ru>
Signed-off-by: Christian Brabandt <cb@256bit.org>
diff --git a/src/os_mswin.c b/src/os_mswin.c
index 95e3cbc..485ee20 100644
--- a/src/os_mswin.c
+++ b/src/os_mswin.c
@@ -2729,8 +2729,8 @@
 }
 
 // The default font height in 100% scaling (96dpi).
-// (-12 in 96dpi equates to roughly 9pt)
-#define DEFAULT_FONT_HEIGHT	(-12)
+// (-16 in 96dpi equates to roughly 12pt)
+#define DEFAULT_FONT_HEIGHT	(-16)
 
 static const LOGFONTW s_lfDefault =
 {