Unconditionally use get_gui_app_args()

Add get_gui_app_args() to the Compiler class so it can be unconditionally
used

mesonbuild/backend/ninjabackend.py

@@ -2234,9 +2234,8 @@ rule FORTRAN_DEP_HACK%s
         if isinstance(target, build.Executable):
             # Currently only used with the Swift compiler to add '-emit-executable'
             commands += linker.get_std_exe_link_args()
-            # If gui_app is significant on this platform
-            if hasattr(linker, 'get_gui_app_args'):
-                commands += linker.get_gui_app_args(target.gui_app)
+            # If gui_app is significant on this platform, add the appropriate linker arguments
+            commands += linker.get_gui_app_args(target.gui_app)
             # If export_dynamic, add the appropriate linker arguments
             if target.export_dynamic:
                 commands += linker.gen_export_dynamic_link_args(self.environment)

mesonbuild/compilers/compilers.py

@@ -1076,6 +1076,9 @@ class Compiler:
     def gnu_symbol_visibility_args(self, vistype):
         return []
 
+    def get_gui_app_args(self, value):
+        return []
+
 GCC_STANDARD = 0
 GCC_OSX = 1
 GCC_MINGW = 2