Prevent compiler from instantiating 3d xforms > max_3d_size

[bHimes]

never used, but a lot of complaints are put out
e.g.

ptxas warning : Value of threads per SM for entry _ZN7FastFFT32block_fft_kernel_R2C_INCREASE_XZIN7cufftdx6detail19fft_block_executionIJNS1_5BlockENS1_9PrecisionIfEENS1_12FFTsPerBlockILj1EEENS1_4SizeILj4096EEENS1_2SMILj800EEENS1_17ElementsPerThreadILj8EEENS1_9DirectionILNS1_13fft_directionE0EEENS1_4TypeILNS1_8fft_typeE0EEEEEENS2_7complexIfEEfEEvPKT1_PT0_NS_8_OffsetsEfiNT_14workspace_typeE is out of range. .minnctapersm and .maxntid will be ignored