cmd/dist: fix cgoTestSO on FreeBSD amd64 with GOHOSTARCH=386
cmd/dist: fix cgoTestSO on FreeBSD amd64 with GOHOSTARCH=386

The cgoTestSO test currently fails when run on FreeBSD amd64 with
GOHOSTARCH=386. This is due to it failing to find the shared object.

On FreeBSD 64-bit architectures, the linker for 32-bit objects
looks for a separate environment variable. Export both LD_LIBRARY_PATH
and LD_32_LIBRARY_PATH on FreeBSD when GOHOSTARCH=386.

Update issue #13873.

Change-Id: I1fb20dd04eb2007061768b2e4530886521813d42
Reviewed-on: https://go-review.googlesource.com/18420
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
Run-TryBot: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>

akutz/go,ganboing/go-esx,polyverse-security/go,suncycheng/go,linux-on-ibm-z/go,sndnvaps/go,goodlang/good,derekmarcotte/go,ganboing/go-esx,Endika/go,4ad/go,cloudflare/go,vsekhar/elastic-go,Samurais/go,codestation/go,polyverse-security/go,golang/go,linux-on-ibm-z/go,vsekhar/elastic-go,binarycrusader/go,nawawi/go,Samurais/go,linux-on-ibm-z/go,akutz/go,cloudflare/go,sndnvaps/go,linux-on-ibm-z/go,nawawi/go,Endika/go,ImJasonH/go,polyverse-security/go,golang/go,derekmarcotte/go,4ad/go,golang/go,vsekhar/elastic-go,vanloswang/go,polyverse-security/go,momchil-velikov/go,polyverse-security/go,CAFxX/go,CAFxX/go,theif519/go,codestation/go,derekmarcotte/go,derekmarcotte/go,suncycheng/go,ImJasonH/go,derekmarcotte/go,josharian/go,cloudflare/go,theif519/go,goodlang/good,vsekhar/elastic-go,Samurais/go,binarycrusader/go,golang/go,Samurais/go,codestation/go,Cofyc/go,4ad/go,miolini/go,codestation/go,goodlang/good,cyberroadie/go,mwhudson/go,suncycheng/go,josharian/go,polyverse-security/go,goodlang/good,goodlang/good,cyberroadie/go,mwhudson/go,mwhudson/go,vsekhar/elastic-go,josharian/go,akutz/go,linux-on-ibm-z/go,suncycheng/go,linux-on-ibm-z/go,Endika/go,sndnvaps/go,momchil-velikov/go,akutz/go,vanloswang/go,josharian/go,binarycrusader/go,4ad/go,josharian/go,theif519/go,CAFxX/go,vsekhar/elastic-go,goodlang/good,ganboing/go-esx,vanloswang/go,ImJasonH/go,sndnvaps/go,vanloswang/go,ganboing/go-esx,cloudflare/go,binarycrusader/go,codestation/go,4ad/go,miolini/go,josharian/go,binarycrusader/go,cyberroadie/go,mwhudson/go,ImJasonH/go,ganboing/go-esx,binarycrusader/go,cloudflare/go,golang/go,nawawi/go,vsekhar/elastic-go,ganboing/go-esx,Cofyc/go,Samurais/go,cyberroadie/go,binarycrusader/go,golang/go,ImJasonH/go,derekmarcotte/go,golang/go,CAFxX/go,nawawi/go,theif519/go,theif519/go,vanloswang/go,suncycheng/go,Cofyc/go,cyberroadie/go,Samurais/go,cyberroadie/go,polyverse-security/go,linux-on-ibm-z/go,CAFxX/go,derekmarcotte/go,Cofyc/go,theif519/go,suncycheng/go,ImJasonH/go,miolini/go,ImJasonH/go,josharian/go,Endika/go,momchil-velikov/go,momchil-velikov/go,mwhudson/go,miolini/go,goodlang/good,4ad/go,CAFxX/go,mwhudson/go,4ad/go,Endika/go,CAFxX/go,momchil-velikov/go,binarycrusader/go,Cofyc/go,ganboing/go-esx,vanloswang/go,miolini/go,nawawi/go,momchil-velikov/go,cloudflare/go,polyverse-security/go,theif519/go,ImJasonH/go,nawawi/go,nawawi/go,mwhudson/go,sndnvaps/go,cyberroadie/go,christopher-henderson/Go,codestation/go,suncycheng/go,momchil-velikov/go,akutz/go,cyberroadie/go,4ad/go,Endika/go,mwhudson/go,sndnvaps/go,ganboing/go-esx,CAFxX/go,akutz/go,Cofyc/go,Samurais/go,Samurais/go,akutz/go,josharian/go,codestation/go,vanloswang/go,Cofyc/go,miolini/go,suncycheng/go,cloudflare/go,Endika/go,sndnvaps/go,derekmarcotte/go,goodlang/good,sndnvaps/go,golang/go,miolini/go,codestation/go,cloudflare/go,momchil-velikov/go,nawawi/go,Endika/go,linux-on-ibm-z/go,theif519/go,miolini/go,Cofyc/go,akutz/go,vsekhar/elastic-go,vanloswang/go