Improve handling of gui_app

This does two things:

 * On windows GCC-like compilers, the subsystem is always explicitly
 specified (either -mwindows or -mconsole). MSVC is already explicit.

 * The gui_app linker flags are now added after those mandated by
 external dependencies. This is because some misguided libraries (such
 as SDL) think that hijacking `main()` and forcing `-mwindows` in link
 flags is clever. We must unconditionally override such misuses to let
 gui_app work as intended.

mesonbuild/backend/ninjabackend.py

@@ -2327,8 +2327,6 @@ 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, 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)
@@ -2361,6 +2359,15 @@ rule FORTRAN_DEP_HACK%s
             raise RuntimeError('Unknown build target type.')
         return commands
 
+    def get_target_type_link_args_post_dependencies(self, target, linker):
+        commands = []
+        if isinstance(target, build.Executable):
+            # If gui_app is significant on this platform, add the appropriate linker arguments.
+            # Unfortunately this can't be done in get_target_type_link_args, because some misguided
+            # libraries (such as SDL2) add -mwindows to their link flags.
+            commands += linker.get_gui_app_args(target.gui_app)
+        return commands
+
     def get_link_whole_args(self, linker, target):
         target_args = self.build_target_link_arguments(linker, target.link_whole_targets)
         return linker.get_link_whole_for(target_args) if len(target_args) else []
@@ -2539,6 +2546,9 @@ rule FORTRAN_DEP_HACK%s
             if need_threads:
                 commands += linker.thread_link_flags(self.environment)
 
+        # Add link args specific to this BuildTarget type that must not be overridden by dependencies
+        commands += self.get_target_type_link_args_post_dependencies(target, linker)
+
         # Add link args for c_* or cpp_* build options. Currently this only
         # adds c_winlibs and cpp_winlibs when building for Windows. This needs
         # to be after all internal and external libraries so that unresolved

mesonbuild/compilers/compilers.py

@@ -1578,8 +1578,8 @@ class GnuLikeCompiler(abc.ABC):
             return ['-Wl,--allow-shlib-undefined']
 
     def get_gui_app_args(self, value):
-        if self.compiler_type.is_windows_compiler and value:
+        if self.compiler_type.is_windows_compiler:
-            return ['-mwindows']
+            return ['-mwindows' if value else '-mconsole']
         return []
 
     def compute_parameters_with_absolute_paths(self, parameter_list, build_dir):