os: fix blockUntilWaitable on freebsd/{386,arm}
os: fix blockUntilWaitable on freebsd/{386,arm}

The previous fix was wrong because it had two misunderstandings on
freebsd32 calling convention like the following:
- 32-bit id1 implies that it is the upper half of 64-bit id, indeed it
  depends on machine endianness.
- 32-bit ARM calling convension doesn't conform to freebsd32_args,
  indeed it does.

This change fixes the bugs and makes blockUntilWaitable work correctly
on freebsd/{386,arm}.

Fixes #16064.

Change-Id: I820c6d01d59a43ac4f2ab381f757c03b14bca75e
Reviewed-on: https://go-review.googlesource.com/24064
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

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