Use GYP rule for Qt MOC only on Telegram project.

Telegram/gyp/Telegram.gyp

@@ -70,6 +70,7 @@
       'telegram_mac.gypi',
       'telegram_linux.gypi',
       'qt.gypi',
+      'qt_moc.gypi',
       'qt_rcc.gypi',
       'codegen_rules.gypi',
     ],

Telegram/gyp/qt.gypi

@@ -252,24 +252,4 @@
       },
     }],
   ],
-
-  'rules': [{
-    'rule_name': 'qt_moc',
-    'extension': 'h',
-    'outputs': [
-      '<(SHARED_INTERMEDIATE_DIR)/<(_target_name)/moc/moc_<(RULE_INPUT_ROOT).cpp',
-    ],
-    'action': [
-      '<(qt_loc)/bin/moc<(exe_ext)',
-
-      # Silence "Note: No relevant classes found. No output generated."
-      '--no-notes',
-
-      '<!@(python -c "for s in \'<@(_defines)\'.split(\' \'): print(\'-D\' + s)")',
-      # '<!@(python -c "for s in \'<@(_include_dirs)\'.split(\' \'): print(\'-I\' + s)")',
-      '<(RULE_INPUT_PATH)',
-      '-o', '<(SHARED_INTERMEDIATE_DIR)/<(_target_name)/moc/moc_<(RULE_INPUT_ROOT).cpp',
-    ],
-    'message': 'Moc-ing <(RULE_INPUT_ROOT).h..',
-  }],
 }

Telegram/gyp/qt_moc.gypi

@@ -0,0 +1,40 @@
+# This file is part of Telegram Desktop,
+# the official desktop version of Telegram messaging app, see https://telegram.org
+#
+# Telegram Desktop is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# It is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# In addition, as a special exception, the copyright holders give permission
+# to link the code of portions of this program with the OpenSSL library.
+#
+# Full license: https://github.com/telegramdesktop/tdesktop/blob/master/LICENSE
+# Copyright (c) 2014 John Preston, https://desktop.telegram.org
+
+{
+  'rules': [{
+    'rule_name': 'qt_moc',
+    'extension': 'h',
+    'outputs': [
+      '<(SHARED_INTERMEDIATE_DIR)/<(_target_name)/moc/moc_<(RULE_INPUT_ROOT).cpp',
+    ],
+    'action': [
+      '<(qt_loc)/bin/moc<(exe_ext)',
+
+      # Silence "Note: No relevant classes found. No output generated."
+      '--no-notes',
+
+      '<!@(python -c "for s in \'<@(_defines)\'.split(\' \'): print(\'-D\' + s)")',
+      # '<!@(python -c "for s in \'<@(_include_dirs)\'.split(\' \'): print(\'-I\' + s)")',
+      '<(RULE_INPUT_PATH)',
+      '-o', '<(SHARED_INTERMEDIATE_DIR)/<(_target_name)/moc/moc_<(RULE_INPUT_ROOT).cpp',
+    ],
+    'message': 'Moc-ing <(RULE_INPUT_ROOT).h..',
+  }],
+}