cmd/link: fix number-of-files entry in gopclntab
cmd/link: fix number-of-files entry in gopclntab

According to golang.org/s/go12symtab, for N files, it should put N+1
there.

Fixes #17132.

Change-Id: I0c84136855c6436be72b9d3c407bf10d4c81a099
Reviewed-on: https://go-review.googlesource.com/29275
Run-TryBot: Cherry Zhang <d62e63aa42ce272d7b6a5055d97e942b33a34679@google.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: David Crawshaw <a2f0bf29257797dd66800b4fbb9945c3e216c004@golang.org>

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