[gtkmm] meson.build: Clean up MSVC build flags

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

commit 496bc8ce68affee80263f1065aa3b69f7f9b6171
Author: Chun-wei Fan <fanchunwei src gnome org>
Date:   Tue May 11 18:13:33 2021 +0800

    meson.build: Clean up MSVC build flags
    
    Like the last NMake Makefiles commit, drop the ignores for warnings C4251,
    C4273 and C4275 as the code is now free of items that trigger those warnings.

 meson.build | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/meson.build b/meson.build
index 220ffe03..89e01c03 100644
--- a/meson.build
+++ b/meson.build
@@ -261,7 +261,7 @@ gui_app_ldflags = []
 #       otherwise the program will fail to link unless we defined a WinMain()
 #       for them
 if is_msvc
-  foreach wd : ['/FImsvc_recommended_pragmas.h', '/wd4267', '/wd4530', '/wd4250', '/wd4251', '/wd4273', 
'/wd4275', '/wd4805']
+  foreach wd : ['/FImsvc_recommended_pragmas.h', '/wd4267', '/EHsc', '/wd4250', '/wd4805']
     disabled_warning = cpp_compiler.get_supported_arguments(wd)
     add_project_arguments(disabled_warning, language: 'cpp')
   endforeach