Flip tangent sign in MikkTSpace

https: //github.com/mrdoob/three.js/issues/11438
Change-Id: Ib85c4ed8fbd0b936216cf4a7e129687c0d28d53d
Reviewed-on: https://kuesa-codereview.kdab.com/c/kuesa/kuesa/+/140
Reviewed-by: Paul Lemire <paul.lemire@kdab.com>

src/core/gltf2importer/meshparser_utils.cpp

@@ -409,7 +409,7 @@ SMikkTSpaceInterface createMikkTSpaceInterface()
         positionHead[0] = fvTangent[0];
         positionHead[1] = fvTangent[1];
         positionHead[2] = fvTangent[2];
-        positionHead[3] = fSign;
+        positionHead[3] = -fSign;
         memcpy(userData->tangentBufferData.data() + vertexIndex * byteStride,
                reinterpret_cast<const char *>(&positionHead[0]),
                sizeof(positionHead));