runtime: print debug info on "base out of range"
runtime: print debug info on "base out of range"

This adds debugging information when we panic with "heapBitsForSpan:
base out of range".

Updates #20259.

Change-Id: I0dc1a106aa9e9531051c7d08867ace5ef230eb3f
Reviewed-on: https://go-review.googlesource.com/43310
Run-TryBot: Austin Clements <7ea35d812706d9213868749011af1ed4fa2f6aa0@google.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Keith Randall <8c99c3a9284e493be632950b84cd789d08ed3e9d@golang.org>

derekmarcotte/go,polyverse-security/go,josharian/go,Cofyc/go,vsekhar/elastic-go,codestation/go,akutz/go,golang/go,Cofyc/go,CAFxX/go,akutz/go,polyverse-security/go,nawawi/go,cloudflare/go,codestation/go,golang/go,ImJasonH/go,derekmarcotte/go,josharian/go,josharian/go,CAFxX/go,golang/go,akutz/go,nawawi/go,derekmarcotte/go,CAFxX/go,nawawi/go,derekmarcotte/go,codestation/go,Cofyc/go,christopher-henderson/Go,CAFxX/go,nawawi/go,golang/go,codestation/go,akutz/go,Cofyc/go,ImJasonH/go,ImJasonH/go,Cofyc/go,vsekhar/elastic-go,Cofyc/go,polyverse-security/go,CAFxX/go,derekmarcotte/go,golang/go,ImJasonH/go,cloudflare/go,Cofyc/go,polyverse-security/go,josharian/go,cloudflare/go,nawawi/go,vsekhar/elastic-go,nawawi/go,golang/go,ImJasonH/go,codestation/go,golang/go,CAFxX/go,cloudflare/go,derekmarcotte/go,akutz/go,akutz/go,derekmarcotte/go,josharian/go,CAFxX/go,akutz/go,cloudflare/go,CAFxX/go,ImJasonH/go,polyverse-security/go,polyverse-security/go,akutz/go,derekmarcotte/go,vsekhar/elastic-go,ImJasonH/go,josharian/go,polyverse-security/go,josharian/go,nawawi/go,nawawi/go,cloudflare/go,vsekhar/elastic-go,codestation/go,ImJasonH/go,polyverse-security/go,cloudflare/go,vsekhar/elastic-go,codestation/go,codestation/go,cloudflare/go,vsekhar/elastic-go,josharian/go,Cofyc/go,golang/go,vsekhar/elastic-go