Convert more files to pure Objective-C

FossilOrigin-Name: 46c577957085f072871cb93b46340fd8349c1e20503a448cc8e6d33ddaea1552

src/meson.build

@@ -4,7 +4,7 @@ executable('client',
     'Client.m',
     'Command.m',
     'ConsoleLine.m',
-    'Cube.mm',
+    'Cube.m',
     'DynamicEntity.m',
     'Entity.m',
     'Identifier.m',
@@ -25,29 +25,29 @@ executable('client',
     'clientextras.m',
     'clientgame.m',
     'clients2c.m',
-    'commands.mm',
+    'commands.m',
     'console.m',
     'editing.m',
     'entities.m',
     'init.mm',
     'menus.m',
     'monster.m',
-    'physics.mm',
-    'rendercubes.mm',
-    'renderextras.mm',
+    'physics.m',
+    'rendercubes.m',
+    'renderextras.m',
     'rendergl.mm',
     'rendermd2.mm',
     'renderparticles.mm',
     'rendertext.mm',
     'rndmap.mm',
     'savegamedemo.mm',
-    'server.mm',
+    'server.m',
     'serverbrowser.mm',
-    'serverms.mm',
-    'serverutil.mm',
-    'sound.mm',
-    'tools.mm',
-    'weapon.mm',
+    'serverms.m',
+    'serverutil.m',
+    'sound.m',
+    'tools.m',
+    'weapon.m',
     'world.mm',
     'worldio.mm',
     'worldlight.mm',
@@ -71,12 +71,12 @@ executable('server',
   [
     'Client.m',
     'ServerEntity.m',
-    'server.mm',
-    'serverms.mm',
-    'serverutil.mm',
-    'tools.mm',
+    'server.m',
+    'serverms.m',
+    'serverutil.m',
+    'tools.m',
   ],
-  objcpp_args: ['-DSTANDALONE'],
+  objc_args: ['-DSTANDALONE'],
   dependencies: [
     objfw_dep,
     sdl_dep