WIP: clang build fixes and workarounds#16

Draft

iburyl wants to merge 13 commits intoVcDevel:masterfrom

iburyl:clang-build

Commits on May 7, 2020

initial clang build fixes and workarounds
iburylov
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second set of fixes
iburylov
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__make_dependent_t fix
iburylov
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Commits on May 8, 2020

constexpr workaround
iburylov
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workaround for _S_absmask issue
iburylov
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Commits on May 13, 2020

make stdx::sin work for float
iburylov
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fixed using nullptr_t in sfinae test
iburylov
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ambiguity refactoring
iburylov
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Commits on May 15, 2020

align ambiguity fix with simd2 branch in gcc
iburylov
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fix clang check
iburylov
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one more clang check fix
iburylov
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Commits on May 19, 2020

__make_array workaround
iburylov
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workaround for unary not
iburylov
committed