runtime: use 64 bit calculation in overLoadFactor
runtime: use 64 bit calculation in overLoadFactor

overLoadFactor used a uintptr for its calculations.
When the number of potential buckets was large,
perhaps due to a coding error or corrupt/malicious user input
leading to a very large map size hint,
this led to overflow on 32 bit systems.
This overflow resulted in an infinite loop.

Prevent it by always using a 64 bit calculation.

Updates #20195

Change-Id: Iaabc710773cd5da6754f43b913478cc5562d89a2
Reviewed-on: https://go-review.googlesource.com/42185
Run-TryBot: Josh Bleecher Snyder <cdc248cc4d32e4fbfe04e45228163bcecd48a0b9@gmail.com>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Keith Randall <8c99c3a9284e493be632950b84cd789d08ed3e9d@golang.org>

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