CMake: Bail when configuring multiple configurations and plain Ninja

Previously configuration would not error out if you configured Qt
with -DCMAKE_CONFIGURATION_TYPES=RelWithDebInfo;Debug -GNinja
instead you would get an error like

 CMake Error at cmake/QtBaseConfigureTests.cmake:51 (message):
 Failed to find compiled architecture detection executable at
 qtbase/build/config.tests/arch/RelWithDebInfo/architecture_test.exe

Note that Qt code tries to find the arch test in a RelWithDebInfo
directory but due to using single-config Ninja,
CMAKE_CONFIGURATION_TYPES is ignored, and the executable is placed
in a non-config specific folder.

Error out early in such a case, and mention that for multi-config
builds, the Ninja Multi-Config generator should be used.

Pick-to: 6.4
Change-Id: I0192185123be563671cbe154f968a03b7458e327
Reviewed-by: Alexey Edelev <alexey.edelev@qt.io>

0 files changed, 0 insertions, 0 deletions