split convolution winograd transform input output

[nihui]

No description provided.

[codecov-commenter]

Codecov Report

Merging #3688 (b453543) into master (32560f4) will decrease coverage by 0.00%.
The diff coverage is 99.75%.

@@            Coverage Diff             @@
##           master    #3688      +/-   ##
==========================================
- Coverage   93.15%   93.14%   -0.01%     
==========================================
  Files         633      647      +14     
  Lines      167696   167439     -257     
==========================================
- Hits       156219   155964     -255     
+ Misses      11477    11475       -2     

Impacted Files	Coverage Δ
src/layer/arm/convolution_arm.cpp	97.14% <ø> (ø)
src/layer/mips/convolution_mips.cpp	97.21% <ø> (ø)
src/layer/riscv/convolution_riscv.cpp	99.07% <ø> (ø)
src/layer/x86/convolution_x86.cpp	97.96% <ø> (ø)
...c/layer/arm/convolution_winograd_transform_bf16s.h	98.30% <98.30%> (ø)
...r/arm/convolution_winograd_transform_pack4_bf16s.h	98.63% <98.63%> (ø)
...c/layer/x86/convolution_winograd_transform_pack4.h	99.04% <99.04%> (ø)
src/layer/arm/convolution_3x3_pack4.h	93.80% <100.00%> (-1.62%)	⬇️
src/layer/arm/convolution_3x3_pack4_bf16s.h	92.59% <100.00%> (-2.24%)	⬇️
src/layer/arm/convolution_3x3_pack4_fp16s.h	99.06% <100.00%> (-0.31%)	⬇️
... and 26 more

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