Allow building both Cocoa and dummy dialog implementations

This allows us to remove platformFilters from the Xcode project, which is not supported in Xcode 12.

Xcode/SDL/SDL.xcodeproj/project.pbxproj

@@ -43,7 +43,7 @@
 		000080903BC03006F24E0000 /* SDL_filesystem.c in Sources */ = {isa = PBXBuildFile; fileRef = 00002B010DB1A70931C20000 /* SDL_filesystem.c */; };
 		000095FA1BDE436CF3AF0000 /* SDL_time.c in Sources */ = {isa = PBXBuildFile; fileRef = 0000641A9BAC11AB3FBE0000 /* SDL_time.c */; };
 		000098E9DAA43EF6FF7F0000 /* SDL_camera.c in Sources */ = {isa = PBXBuildFile; fileRef = 0000035D38C3899C7EFD0000 /* SDL_camera.c */; };
-		0000A4DA2F45A31DC4F00000 /* SDL_sysmain_callbacks.m in Sources */ = {isa = PBXBuildFile; fileRef = 0000BB287BA0A0178C1A0000 /* SDL_sysmain_callbacks.m */; platformFilters = (ios, maccatalyst, macos, tvos, watchos, ); };
+		0000A4DA2F45A31DC4F00000 /* SDL_sysmain_callbacks.m in Sources */ = {isa = PBXBuildFile; fileRef = 0000BB287BA0A0178C1A0000 /* SDL_sysmain_callbacks.m */; };
 		0000D5B526B85DE7AB1C0000 /* SDL_cocoapen.m in Sources */ = {isa = PBXBuildFile; fileRef = 0000CCA310B73A7B59910000 /* SDL_cocoapen.m */; };
 		007317A40858DECD00B2BC32 /* Cocoa.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 0073179D0858DECD00B2BC32 /* Cocoa.framework */; platformFilters = (macos, ); };
 		007317A60858DECD00B2BC32 /* IOKit.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 0073179F0858DECD00B2BC32 /* IOKit.framework */; platformFilters = (ios, maccatalyst, macos, ); };
@@ -421,8 +421,8 @@
 		F37A8E1A28405AA100C38E95 /* CMake in Resources */ = {isa = PBXBuildFile; fileRef = F37A8E1928405AA100C38E95 /* CMake */; };
 		F37E184E2B8C097D0098C111 /* SDL_camera.h in Headers */ = {isa = PBXBuildFile; fileRef = 000084ED0A56E3ED52F90000 /* SDL_camera.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		F37E18522BA50E760098C111 /* SDL_dialog.h in Headers */ = {isa = PBXBuildFile; fileRef = F37E18512BA50E750098C111 /* SDL_dialog.h */; settings = {ATTRIBUTES = (Public, ); }; };
-		F37E18582BA50F3B0098C111 /* SDL_cocoadialog.m in Sources */ = {isa = PBXBuildFile; fileRef = F37E18572BA50F3B0098C111 /* SDL_cocoadialog.m */; platformFilters = (macos, ); };
-		F37E185A2BA50F450098C111 /* SDL_dummydialog.c in Sources */ = {isa = PBXBuildFile; fileRef = F37E18592BA50F450098C111 /* SDL_dummydialog.c */; platformFilters = (ios, maccatalyst, tvos, xros, ); };
+		F37E18582BA50F3B0098C111 /* SDL_cocoadialog.m in Sources */ = {isa = PBXBuildFile; fileRef = F37E18572BA50F3B0098C111 /* SDL_cocoadialog.m */; };
+		F37E185A2BA50F450098C111 /* SDL_dummydialog.c in Sources */ = {isa = PBXBuildFile; fileRef = F37E18592BA50F450098C111 /* SDL_dummydialog.c */; };
 		F37E185C2BAA3EF90098C111 /* SDL_time.h in Headers */ = {isa = PBXBuildFile; fileRef = F37E185B2BAA3EF90098C111 /* SDL_time.h */; settings = {ATTRIBUTES = (Public, ); }; };
 		F37E18622BAA40090098C111 /* SDL_sysfilesystem.h in Headers */ = {isa = PBXBuildFile; fileRef = F37E18612BAA40090098C111 /* SDL_sysfilesystem.h */; };
 		F37E18642BAA40670098C111 /* SDL_time_c.h in Headers */ = {isa = PBXBuildFile; fileRef = F37E18632BAA40670098C111 /* SDL_time_c.h */; };

include/build_config/SDL_build_config_ios.h

@@ -227,4 +227,6 @@
 
 #define SDL_CAMERA_DRIVER_DUMMY 1
 
+#define SDL_DIALOG_DUMMY 1
+
 #endif /* SDL_build_config_ios_h_ */

src/dialog/cocoa/SDL_cocoadialog.m

@@ -21,6 +21,8 @@
 #include "SDL_internal.h"
 #include "../SDL_dialog_utils.h"
 
+#ifdef SDL_PLATFORM_MACOS
+
 #import <Cocoa/Cocoa.h>
 #import <UniformTypeIdentifiers/UTType.h>
 
@@ -33,10 +35,6 @@ typedef enum
 
 void show_file_dialog(cocoa_FileDialogType type, SDL_DialogFileCallback callback, void* userdata, SDL_Window* window, const SDL_DialogFileFilter *filters, int nfilters, const char* default_location, bool allow_many)
 {
-#if defined(SDL_PLATFORM_TVOS) || defined(SDL_PLATFORM_IOS)
-    SDL_SetError("tvOS and iOS don't support path-based file dialogs");
-    callback(userdata, NULL, -1);
-#else
     if (filters) {
         const char *msg = validate_filters(filters, nfilters);
 
@@ -175,7 +173,6 @@ void show_file_dialog(cocoa_FileDialogType type, SDL_DialogFileCallback callback
             callback(userdata, files, -1);
         }
     }
-#endif // defined(SDL_PLATFORM_TVOS) || defined(SDL_PLATFORM_IOS)
 }
 
 void SDL_ShowOpenFileDialog(SDL_DialogFileCallback callback, void* userdata, SDL_Window* window, const SDL_DialogFileFilter *filters, int nfilters, const char* default_location, bool allow_many)
@@ -192,3 +189,5 @@ void SDL_ShowOpenFolderDialog(SDL_DialogFileCallback callback, void* userdata, S
 {
     show_file_dialog(FDT_OPENFOLDER, callback, userdata, window, NULL, 0, default_location, allow_many);
 }
+
+#endif // SDL_PLATFORM_MACOS

src/dialog/dummy/SDL_dummydialog.c

@@ -20,6 +20,8 @@
 */
 #include "SDL_internal.h"
 
+#ifdef SDL_DIALOG_DUMMY
+
 void SDL_ShowOpenFileDialog(SDL_DialogFileCallback callback, void* userdata, SDL_Window* window, const SDL_DialogFileFilter *filters, int nfilters, const char* default_location, bool allow_many)
 {
   SDL_Unsupported();
@@ -37,3 +39,5 @@ void SDL_ShowOpenFolderDialog(SDL_DialogFileCallback callback, void* userdata, S
   SDL_Unsupported();
   callback(userdata, NULL, -1);
 }
+
+#endif // SDL_DIALOG_DUMMY