Fix build with clang-cl and the Intel compiler on Windows

Neither clang-cl nor the Intel compiler are able to parse the MSVC code
in a constexpr environment. For Clang, we can just use the __builtin
functions, which it does make available on Windows. For the Intel
compiler, there's no alternative, so we just don't use the _BitScanXxx
functions. It will produce slower code, though.

qalgorithms.h(587,19) :  error: variables defined in a constexpr function must be initialized
qalgorithms.h(635,12) :  note: non-constexpr function '__popcnt' cannot be used in a constant expression

etc.

Change-Id: I149e0540c00745fe8119fffd14627ded43807000
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@theqtcompany.com>
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

0 files changed, 0 insertions, 0 deletions