Fix for GCC

[Jamaika1]

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[jan-wassenberg]

Hi @Jamaika1 , thanks for sending. We will make a larger change that only uses _Float16 when required, instead of opting out like now. Please see #846.

[Jamaika1]

Hi @jan-wassenberg. I need confirmation. Do the files created by me work under Windows 64bit AVX2? https://www.sendspace.com/file/6p4fzw Can function {mavx2} not be used for gcc? How then to define the highway?