CMake: Unify CMAKE_BUILD_TYPE behavior on all platforms

Before this change, we had the following behaviors.

On platforms other than Windows-MSVC:
- when no build type was specified, we defaulted to Release
- when -developer-build was specified, we defaulted to Debug
- regardless of platform, unless the option was explicitly specified,
we never defaulted to -debug-and-release.

On Windows-MSVC, we always defaulted to Debug. Which is inconsistent
with the rules above.
The difference happens because CMake always sets CMAKE_BUILD_TYPE to
Debug during the first project() call when targeting the Windows-MSVC
platform.

We interpreted that as the user setting the build type, and thus we
didn't want to override what the user specified.

After this change, if we detect that it's cmake setting the build
type, we assign a build type that follows the non-Windows-MSVC rules.

This change unifies the behavior across all platforms.

Adjusted the configure help with the new reality.

Augments 33af62db3747bb6fcb7490ef2d2abc5bb53925b6

[ChangeLog][configure] When no explicit build type is specified,
Windows will now default to building Release like the other
platforms.

Pick-to: 6.5 6.6
Change-Id: Id2bf269c51cf300ec09751ece2ad721869e0f90c
Reviewed-by: Amir Masoud Abdol <amir.abdol@qt.io>
Reviewed-by: Joerg Bornemann <joerg.bornemann@qt.io>

0 files changed, 0 insertions, 0 deletions