Fix compilation of kiwix-lib-app.

- We should not try to set the cross compilation flags when we use
  gradle.
- Fix anyway the setting of tho cross compilation flags for android sdk
  platform (the default implementation use the `static` attributes that
  doesn't exist for android)

kiwixbuild/dependencies/base.py

@@ -524,5 +524,5 @@ class GradleBuilder(Builder):
         command = command.format(
             gradle_target=self.gradle_target,
             gradle_option=self.gradle_option)
-        env = self.buildEnv.get_env(cross_comp_flags=True, cross_compilers=True, cross_path=True)
+        env = self.buildEnv.get_env(cross_comp_flags=False, cross_compilers=True, cross_path=True)
         run_command(command, self.build_path, context, env=env)

kiwixbuild/platforms/android.py

@@ -145,3 +145,6 @@ class Android(MetaPlatformInfo):
         env = super().get_env()
         env['ANDROID_HOME'] = self.sdk_builder.install_path
         return env
+
+    def set_comp_flags(self, env):
+        pass