cmd/cgo: add missing formatting directive in error message
cmd/cgo: add missing formatting directive in error message

Fixes #15310.

Change-Id: I588b3c630a20a6878f7cd00f9af29b1dd8a4abf6
Reviewed-on: https://go-review.googlesource.com/22100
Run-TryBot: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

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