Update instructions on how to build protoc-mingw.exe.
Update instructions on how to build protoc-mingw.exe.

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MOS_MIGRATED_REVID=133842785

kchodorow/bazel-1,dropbox/bazel,spxtr/bazel,hermione521/bazel,davidzchen/bazel,aehlig/bazel,Asana/bazel,snnn/bazel,cushon/bazel,dslomov/bazel,cushon/bazel,mbrukman/bazel,LuminateWireless/bazel,damienmg/bazel,variac/bazel,variac/bazel,snnn/bazel,mrdomino/bazel,aehlig/bazel,Asana/bazel,katre/bazel,kchodorow/bazel-1,iamthearm/bazel,mrdomino/bazel,dslomov/bazel,hermione521/bazel,zhexuany/bazel,mikelikespie/bazel,ButterflyNetwork/bazel,kchodorow/bazel,mbrukman/bazel,spxtr/bazel,davidzchen/bazel,werkt/bazel,kchodorow/bazel,kchodorow/bazel-1,dslomov/bazel-windows,snnn/bazel,aehlig/bazel,dslomov/bazel-windows,twitter-forks/bazel,twitter-forks/bazel,damienmg/bazel,hermione521/bazel,kchodorow/bazel,bazelbuild/bazel,ulfjack/bazel,LuminateWireless/bazel,katre/bazel,juhalindfors/bazel-patches,dslomov/bazel-windows,zhexuany/bazel,perezd/bazel,hermione521/bazel,Asana/bazel,ButterflyNetwork/bazel,dslomov/bazel,LuminateWireless/bazel,werkt/bazel,aehlig/bazel,dslomov/bazel,safarmer/bazel,werkt/bazel,ButterflyNetwork/bazel,werkt/bazel,juhalindfors/bazel-patches,iamthearm/bazel,mbrukman/bazel,kchodorow/bazel-1,mikelikespie/bazel,juhalindfors/bazel-patches,snnn/bazel,variac/bazel,bazelbuild/bazel,Asana/bazel,davidzchen/bazel,akira-baruah/bazel,mbrukman/bazel,safarmer/bazel,safarmer/bazel,iamthearm/bazel,dslomov/bazel,mikelikespie/bazel,cushon/bazel,LuminateWireless/bazel,damienmg/bazel,akira-baruah/bazel,meteorcloudy/bazel,zhexuany/bazel,damienmg/bazel,damienmg/bazel,kchodorow/bazel,twitter-forks/bazel,mrdomino/bazel,twitter-forks/bazel,zhexuany/bazel,perezd/bazel,davidzchen/bazel,zhexuany/bazel,juhalindfors/bazel-patches,perezd/bazel,twitter-forks/bazel,safarmer/bazel,mbrukman/bazel,ulfjack/bazel,spxtr/bazel,cushon/bazel,aehlig/bazel,dropbox/bazel,ButterflyNetwork/bazel,mikelikespie/bazel,mikelikespie/bazel,hermione521/bazel,katre/bazel,Asana/bazel,zhexuany/bazel,bazelbuild/bazel,akira-baruah/bazel,mrdomino/bazel,twitter-forks/bazel,variac/bazel,safarmer/bazel,kchodorow/bazel,ulfjack/bazel,spxtr/bazel,dslomov/bazel-windows,LuminateWireless/bazel,akira-baruah/bazel,hermione521/bazel,meteorcloudy/bazel,iamthearm/bazel,dslomov/bazel,aehlig/bazel,ButterflyNetwork/bazel,mbrukman/bazel,aehlig/bazel,snnn/bazel,dropbox/bazel,mikelikespie/bazel,juhalindfors/bazel-patches,Asana/bazel,ulfjack/bazel,akira-baruah/bazel,bazelbuild/bazel,snnn/bazel,meteorcloudy/bazel,katre/bazel,dropbox/bazel,variac/bazel,variac/bazel,kchodorow/bazel,meteorcloudy/bazel,ulfjack/bazel,iamthearm/bazel,ButterflyNetwork/bazel,akira-baruah/bazel,damienmg/bazel,mrdomino/bazel,mrdomino/bazel,davidzchen/bazel,perezd/bazel,kchodorow/bazel-1,dslomov/bazel-windows,spxtr/bazel,kchodorow/bazel-1,safarmer/bazel,spxtr/bazel,meteorcloudy/bazel,iamthearm/bazel,perezd/bazel,ulfjack/bazel,katre/bazel,cushon/bazel,damienmg/bazel,perezd/bazel,perezd/bazel,kchodorow/bazel,davidzchen/bazel,werkt/bazel,meteorcloudy/bazel,meteorcloudy/bazel,twitter-forks/bazel,juhalindfors/bazel-patches,cushon/bazel,juhalindfors/bazel-patches,ulfjack/bazel,katre/bazel,bazelbuild/bazel,dropbox/bazel,variac/bazel,dropbox/bazel,bazelbuild/bazel,davidzchen/bazel,LuminateWireless/bazel,dslomov/bazel,snnn/bazel,dslomov/bazel-windows,spxtr/bazel,Asana/bazel,werkt/bazel