Create os and arch variants for GoBinaryTool modules

AddFarVariationDependencies was broken, which allowed modules to add
dependencies on GoBinaryTool modules using os and arch variations
even though GoBinaryTool modules did not have any variations.  Mutate
GoBinaryTool modules in the os and arch mutators so that they have the
expected os and arch variations.

Test: all soong tests
Change-Id: Ida7bc75a51ab1d2d38a6be11f574399097380cc9