Replace genrule in go_yacc with custom bzl rule. (#841)
Replace genrule in go_yacc with custom bzl rule. (#841)

genrules require a bash shell, making them incompatible with
Windows unless a mingw dependency is added.

I made the private rule 1:1 compatible with the previous macro genrule
implementation in case there are some dependent repositories that use it.
bazelbuild/buildtools,bazelbuild/buildtools,bazelbuild/buildtools,bazelbuild/buildtools,bazelbuild/buildtools