meson: Specify encoding to UTF-8 when building with MSVC

Fix build on some non-US locale Windows systems

Error:
  gst-plugins-base/tools/gst-device-monitor.c(278): error C2001

https://bugzilla.gnome.org/show_bug.cgi?id=797186

meson.build

@@ -46,6 +46,7 @@ if cc.get_id() == 'msvc'
       '/wd4146', # unary minus on unsigned (beware INT_MIN)
       '/wd4244', # lossy type conversion (e.g. double -> int)
       '/wd4305', # truncating type conversion (e.g. double -> float)
+      cc.get_supported_arguments(['/utf-8']), # set the input encoding to utf-8
       language : 'c')
   # Disable SAFESEH with MSVC for plugins and libs that use external deps that
   # are built with MinGW