elu 4d and selu 4d

[nihui]

No description provided.

[codecov-commenter]

Codecov Report

Merging #5047 (546bfd0) into master (fdf2c48) will decrease coverage by 0.25%.
Report is 2 commits behind head on master.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #5047      +/-   ##
==========================================
- Coverage   94.72%   94.48%   -0.25%     
==========================================
  Files         765      767       +2     
  Lines      229654   229724      +70     
==========================================
- Hits       217551   217051     -500     
- Misses      12103    12673     +570     

Files Changed	Coverage Δ
src/layer/elu.cpp	100.00% <100.00%> (ø)
src/layer/x86/elu_x86.cpp	100.00% <100.00%> (ø)

... and 55 files with indirect coverage changes