cmd/go: remove .o and .a files in builder.collect
cmd/go: remove .o and .a files in builder.collect

This matches the removal of .so files and makes the processing
of '-L/path/to -lfoo' and plain '/path/to/foo.a' match.

Fixes #16463.

Change-Id: I1464c5390d7eb6a3a33b4b2c951f87ef392ec94a
Reviewed-on: https://go-review.googlesource.com/32642
Run-TryBot: Russ Cox <5ad239cb8a44f659eaaee0aa1ea5b94947abe557@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>

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