BENCH: add correlate/convolve benchmarks.
BENCH: add correlate/convolve benchmarks.

Related to gh-5978, which makes significant changes to these functions.

chatcannon/numpy,madphysicist/numpy,ahaldane/numpy,dwillmer/numpy,abalkin/numpy,endolith/numpy,behzadnouri/numpy,rgommers/numpy,bertrand-l/numpy,AustereCuriosity/numpy,MSeifert04/numpy,jakirkham/numpy,SiccarPoint/numpy,skwbc/numpy,dwillmer/numpy,jakirkham/numpy,rgommers/numpy,charris/numpy,tacaswell/numpy,mattip/numpy,gmcastil/numpy,mhvk/numpy,pdebuyl/numpy,simongibbons/numpy,mhvk/numpy,maniteja123/numpy,endolith/numpy,WarrenWeckesser/numpy,SiccarPoint/numpy,mhvk/numpy,pizzathief/numpy,gfyoung/numpy,simongibbons/numpy,joferkington/numpy,tynn/numpy,madphysicist/numpy,ssanderson/numpy,AustereCuriosity/numpy,numpy/numpy,ContinuumIO/numpy,joferkington/numpy,numpy/numpy,pdebuyl/numpy,jorisvandenbossche/numpy,charris/numpy,seberg/numpy,stuarteberg/numpy,bringingheavendown/numpy,grlee77/numpy,anntzer/numpy,simongibbons/numpy,seberg/numpy,numpy/numpy,bertrand-l/numpy,behzadnouri/numpy,solarjoe/numpy,jorisvandenbossche/numpy,stuarteberg/numpy,Eric89GXL/numpy,endolith/numpy,madphysicist/numpy,pbrod/numpy,madphysicist/numpy,tynn/numpy,jakirkham/numpy,pizzathief/numpy,grlee77/numpy,shoyer/numpy,ContinuumIO/numpy,jorisvandenbossche/numpy,anntzer/numpy,kiwifb/numpy,kiwifb/numpy,maniteja123/numpy,grlee77/numpy,WarrenWeckesser/numpy,gfyoung/numpy,MSeifert04/numpy,b-carter/numpy,shoyer/numpy,gmcastil/numpy,MSeifert04/numpy,mattip/numpy,pdebuyl/numpy,ahaldane/numpy,skwbc/numpy,pizzathief/numpy,MSeifert04/numpy,Eric89GXL/numpy,njase/numpy,shoyer/numpy,simongibbons/numpy,jorisvandenbossche/numpy,abalkin/numpy,b-carter/numpy,njase/numpy,anntzer/numpy,ahaldane/numpy,WarrenWeckesser/numpy,seberg/numpy,pbrod/numpy,stuarteberg/numpy,utke1/numpy,tacaswell/numpy,pdebuyl/numpy,ddasilva/numpy,seberg/numpy,njase/numpy,charris/numpy,bringingheavendown/numpy,tynn/numpy,shoyer/numpy,anntzer/numpy,simongibbons/numpy,gfyoung/numpy,utke1/numpy,skwbc/numpy,chatcannon/numpy,behzadnouri/numpy,rgommers/numpy,ddasilva/numpy,numpy/numpy,dwillmer/numpy,jakirkham/numpy,WarrenWeckesser/numpy,Eric89GXL/numpy,tacaswell/numpy,jakirkham/numpy,grlee77/numpy,maniteja123/numpy,abalkin/numpy,WarrenWeckesser/numpy,chatcannon/numpy,endolith/numpy,gmcastil/numpy,MSeifert04/numpy,pizzathief/numpy,charris/numpy,ssanderson/numpy,solarjoe/numpy,grlee77/numpy,bringingheavendown/numpy,pbrod/numpy,ahaldane/numpy,b-carter/numpy,stuarteberg/numpy,jorisvandenbossche/numpy,joferkington/numpy,pizzathief/numpy,rgommers/numpy,ContinuumIO/numpy,mhvk/numpy,Eric89GXL/numpy,solarjoe/numpy,joferkington/numpy,SiccarPoint/numpy,mhvk/numpy,ssanderson/numpy,utke1/numpy,bertrand-l/numpy,ahaldane/numpy,shoyer/numpy,dwillmer/numpy,pbrod/numpy,SiccarPoint/numpy,pbrod/numpy,mattip/numpy,ddasilva/numpy,mattip/numpy,madphysicist/numpy,kiwifb/numpy,AustereCuriosity/numpy