meson/MSVC builds: Use -utf-8 where available

This avoids the build from erroring out on C4819 (Unicode handling issue in
Visual Studio compiler), notably when running on CHinese, Japanese and
Korean locales.

meson.build

@@ -274,9 +274,12 @@ endif
 if cc.get_id() == 'msvc'
   # Compiler options taken from msvc_recommended_pragmas.h
   # in GLib, based on _Win32_Programming_ by Rector and Newcomer
-  test_cflags = []
-  add_project_arguments('-FImsvc_recommended_pragmas.h', language: 'c')
-  add_project_arguments('-D_USE_MATH_DEFINES', language: 'c')
+  test_cflags = [
+    '-FImsvc_recommended_pragmas.h',
+	'-D_USE_MATH_DEFINES',
+	'-utf-8',
+  ]
+  add_project_arguments(cc.get_supported_arguments(test_cflags), language: 'c')
 elif cc.get_id() == 'gcc' or cc.get_id() == 'clang'
   test_cflags = [
     '-fno-strict-aliasing',