Use Meson get_argument_syntax()

Newer versions of Meson introduce a more reliable way to detect
the compiler's expected command-line argument style.

meson.build

@@ -6,8 +6,7 @@ add_project_arguments(
     language: 'c',
 )
 
-# Use get_argument_syntax() instead once Meson 0.49.0 releases
-if meson.get_compiler('c').get_id() != 'msvc'
+if meson.get_compiler('c').get_argument_syntax() != 'msvc'
     add_project_arguments(
         '-Wall',
         '-ffunction-sections',