Install Qt to global prefix in Dockerfile

Telegram/build/docker/centos_env/Dockerfile

@@ -722,6 +722,7 @@ RUN git clone -b {{ QT_TAG }} --depth=1 {{ GIT }}/qt/qt5.git \
 	&& find ../../patches/qtwayland_{{ QT }} -type f -print0 | sort -z | xargs -r0 git apply \
 	&& cd .. \
 	&& cmake -B build . \
+		-DCMAKE_INSTALL_PREFIX=/usr/local \
 		-DBUILD_SHARED_LIBS=OFF \
 		-DQT_GENERATE_SBOM=OFF \
 		-DINPUT_libpng=qt \
@@ -868,7 +869,6 @@ COPY --link --from=ada {{ LibrariesPath }}/ada-cache /
 COPY --link --from=tde2e {{ LibrariesPath }}/tde2e-cache /
 
 WORKDIR ../tdesktop
-ENV QT {{ QT }}
 ENV BOOST_INCLUDEDIR /usr/include/boost1.78
 ENV BOOST_LIBRARYDIR /usr/lib64/boost1.78
 

Telegram/build/qt_version.py

@@ -5,10 +5,9 @@ def resolve(arch):
         os.environ['QT'] = '6.2.12'
     elif sys.platform == 'win32':
         if arch == 'arm' or 'qt6' in sys.argv:
+            print('Choosing Qt 6.')
             os.environ['QT'] = '6.9.0'
-        elif os.environ.get('QT') is None:
+        else:
+            print('Choosing Qt 5.')
             os.environ['QT'] = '5.15.15'
-    elif os.environ.get('QT') is None:
-        return False
-    print('Choosing Qt ' + os.environ.get('QT'))
     return True