Clang wrapper for Linux and Windows should set `_GLIBCXX_USE_CXX11_ABI`

[giordano]

At the moment

BinaryBuilderBase.jl/src/Runner.jl

Lines 462 to 467 in f782dc5

	# Force proper cxx11 string ABI usage w00t w00t!
	if cxxstring_abi(p) == "cxx11"
	push!(flags, "-D_GLIBCXX_USE_CXX11_ABI=1")
	elseif cxxstring_abi(p) == "cxx03"
	push!(flags, "-D_GLIBCXX_USE_CXX11_ABI=0")
	end

is done only for GCC, but it should be done also for Clang on Linux and Windows, since in that case we use libstdc+.