cmd/pprof: ignore symbols with address 0 and size 0
cmd/pprof: ignore symbols with address 0 and size 0

Handling a symbol with address 0 and size 0, such as an ELF STT_FILE
symbols, was causing us to disassemble the entire program.  We started
adding STT_FILE symbols to help fix issue #13247.

Fixes #16154.

Change-Id: I174b9614e66ddc3d65801f7c1af7650f291ac2af
Reviewed-on: https://go-review.googlesource.com/24460
Run-TryBot: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Joe Tsai <7277d7402195d5c2006c89f45718cf82bb3e527f@gmail.com>

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