tests/d3d12: Avoid out-of-bounds access when evaluating ok() args (ubsan).
Compiling and running with UBSan reported the following errors:
tests/d3d12.c:31063:5: runtime error: index 4 out of bounds for type 'float [4][8]'
tests/d3d12.c:31063:5: runtime error: index 8 out of bounds for type 'float [8]'
tests/d3d12.c:31063:5: runtime error: load of address 0x557ee85a1500 with insufficient space for an object of type 'const float'
tests/d3d12.c:31248:5: runtime error: index 4 out of bounds for type 'float [4][4]'
tests/d3d12.c:31248:5: runtime error: index 4 out of bounds for type 'float [4]'
tests/d3d12.c:31248:5: runtime error: load of address 0x557ee85a10d0 with insufficient space for an object of type 'const float'