vala: Pass --shared-library to valac when generating a .gir file

This is required to make sure that the generated .gir file actually contains all
the information to be used dynamically.

Valac supports this argument since 0.29.3 released in 2015.

Author: tintou

mesonbuild/backend/ninjabackend.py

@@ -1765,6 +1765,9 @@ def generate_vala_compile(self, target: build.BuildTarget) -> \
                 girname = os.path.join(self.get_target_dir(target), target.vala_gir)
                 args += ['--gir', os.path.join('..', target.vala_gir)]
                 valac_outputs.append(girname)
+                shared_target = target.get('shared')
+                if isinstance(shared_target, build.SharedLibrary):
+                    args += ['--shared-library', self.get_target_filename_for_linking(shared_target)]
                 # Install GIR to default location if requested by user
                 if len(target.install_dir) > 3 and target.install_dir[3] is True:
                     target.install_dir[3] = os.path.join(self.environment.get_datadir(), 'gir-1.0')