Fix -debug-and-release on Linux

$ ./configure -opensource -confirm-license -debug-and-release
...
WARNING: -debug-and-release is only supported on Darwin and Windows platforms.  Qt can be built in release mode with separate debug information, so -debug-and-release is no longer necessary.

ERROR: Feature 'debug_and_release' was enabled, but the pre-condition 'config.darwin || config.win32' failed.

$ /configure -debug-and-release

+ cd qtbase
+ /home/qt/depot/tmp/qt5/qtbase/configure -top-level -debug-and-release
'/usr/bin/cmake' '-DCMAKE_CONFIGURATION_TYPES=Debug;Release' '-G' 'Unix Makefiles' '/home/qt/depot/tmp/qt5'
-- The CXX compiler identification is GNU 7.5.0
-- The C compiler identification is GNU 7.5.0
-- The ASM compiler identification is GNU
-- Found assembler: /usr/bin/cc
-- Detecting CXX compiler ABI info
-- Detecting CXX compiler ABI info - done
-- Check for working CXX compiler: /usr/bin/c++ - skipped
-- Detecting CXX compile features
-- Detecting CXX compile features - done
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Check for working C compiler: /usr/bin/cc - skipped
-- Detecting C compile features
-- Detecting C compile features - done
-- Building for multiple configurations: Debug;Release.
-- Main configuration is: Debug.
CMake Error at qtbase/cmake/QtBaseConfigureTests.cmake:40 (message):
  Failed to find compiled architecture detection executable at
  /home/qt/depot/tmp/qt5/qtbase/config.tests/arch/Debug/architecture_test.
Call Stack (most recent call first):
  qtbase/cmake/QtBaseConfigureTests.cmake:119 (qt_run_config_test_architecture)
  qtbase/cmake/QtBaseConfigureTests.cmake:132 (qt_run_qtbase_config_tests)
  qtbase/CMakeLists.txt:76 (include)


-- Configuring incomplete, errors occurred!
See also "/home/qt/depot/tmp/qt5/CMakeFiles/CMakeOutput.log".
CMake Error at qtbase/cmake/QtProcessConfigureArgs.cmake:751 (message):
  CMake exited with code 1.