api: add Fchflags exception to more platforms
api: add Fchflags exception to more platforms

Unbreaks the build.

R=golang-codereviews, dsymonds
CC=golang-codereviews
https://codereview.appspot.com/53820045

apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang,apparentlymart/golang