runtime: rename the TestGcHashmapIndirection to TestGcMapIndirection
runtime: rename the TestGcHashmapIndirection to TestGcMapIndirection

There was still the word 'Hashmap' in gc_test.go, so I renamed it to just 'Map'

Previous renaming commit: https://golang.org/cl/90336

Change-Id: I5b0e5c2229d1c30937c7216247f4533effb81ce7
Reviewed-on: https://go-review.googlesource.com/96675
Reviewed-by: Brad Fitzpatrick <ae9783c0b0efc69cd85ab025ddd17aa44cdc4aa5@golang.org>

josharian/go,akutz/go,golang/go,CAFxX/go,nawawi/go,golang/go,josharian/go,codestation/go,golang/go,josharian/go,cloudflare/go,codestation/go,Cofyc/go,golang/go,golang/go,CAFxX/go,nawawi/go,Cofyc/go,cloudflare/go,cloudflare/go,nawawi/go,CAFxX/go,josharian/go,nawawi/go,cloudflare/go,cloudflare/go,Cofyc/go,codestation/go,Cofyc/go,nawawi/go,CAFxX/go,josharian/go,codestation/go,akutz/go,Cofyc/go,josharian/go,nawawi/go,golang/go,nawawi/go,codestation/go,cloudflare/go,CAFxX/go,CAFxX/go,akutz/go,codestation/go,CAFxX/go,codestation/go,cloudflare/go,Cofyc/go,Cofyc/go,akutz/go,akutz/go,josharian/go,akutz/go,cloudflare/go,nawawi/go,golang/go,Cofyc/go,golang/go,CAFxX/go,akutz/go,josharian/go,akutz/go,codestation/go