[gtkmm/use-dllexport-3-24-meson: 1/16] NMake Makefiles: Use /utf-8 if available

[Chun-wei Fan <fanchunwei src gnome org>]

commit f1aacdd8cb9d799e3b3c4641298b7fc892205287
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Wed May 13 11:10:33 2020 +0800

    NMake Makefiles: Use /utf-8 if available
    
    This flag is provided on Visual Studio 2015 and later, so that it will help to
    work around unicode handling issues that occur when building on East Asian
    locales, that is demonstrated by error/warning C4819.
    
    Disabling warning C4828 is meant for gendef.exe, which comes as a consequence
    of using /utf-8.

 MSVC_NMake/config-msvc.mak | 6 ++++++
 1 file changed, 6 insertions(+)
---
diff --git a/MSVC_NMake/config-msvc.mak b/MSVC_NMake/config-msvc.mak
index 9dce22d4..444a729e 100644
--- a/MSVC_NMake/config-msvc.mak
+++ b/MSVC_NMake/config-msvc.mak
@@ -128,6 +128,12 @@ GDKMM_BASE_CFLAGS =                \
        /wd4530 /wd4251 /wd4275 \
        /FImsvc_recommended_pragmas.h
 
+!if $(PDBVER) > 14
+GDKMM_BASE_CFLAGS =            \
+       $(GDKMM_BASE_CFLAGS)    \
+       /utf-8 /wd4828  \
+!endif
+
 GTKMM_BASE_CFLAGS =            \
        /Ivs$(PDBVER)\$(CFG)\$(PLAT)    \
        /I..\gtk /I.\gtkmm      \