support for UV mirroring on UsdUVTexture

[pmolodo]

...when exporting / importing.

Also does a bit of code unification for U+V cases

[JGamache-autodesk]

The Windows build has failed:
maya-usd\lib\usd\translators\shading\usdFileTextureWriter.cpp(445): error C4576: a parenthesized type followed by an initializer list is a non-standard explicit type conversion syntax
maya-usd\lib\usd\translators\shading\usdFileTextureWriter.cpp(445): fatal error C1001: An internal error has occurred in the compiler.
It was nice to see this elegant initializer syntax in the loops, but it seems VS does not understand it.

[kxl-adsk]

I commented in one place where PF caught error - please check logs if you need more details.

BTW. We still have issues with some windows nodes, so apologies for the inconvenience.

[kxl-adsk]

We are still having trouble with windows nodes, but in this case PF actually found something real.

S:\jenkins\workspace\ecg-mayausd-branch-preflight-2020-windows\ecg-maya-usd\maya-usd\lib\usd\translators\shading\usdUVTextureReader.cpp(316): error C4576: a parenthesized type followed by an initializer list is a non-standard explicit type conversion syntax

[pmolodo]

Hmm, sorry about that. I guess the initializer syntax I used was not strict c++11, but a gcc extension:

(const TfToken[2][3]){ ... }

I just ended up declaring a variable to hold the array. Alternatively, I could apparently have declared a type alias, since it seems that

T{ ... }

is valid, but only if T is a "simple-type-specifier". So I could have done:

using Token23 = const TfToken[2][3];
for (auto wrapMirrorTriple : Token23{ ... }) {

...but I decided at that point it was just simpler to make the variable...

(Thanks to this post for the info about simple-type-specifiers: https://stackoverflow.com/a/24390563/920545)