fails with clang not found

[rakyll]

go2xcode golang.org/x/mobile/exp/sensor/example
# runtime/cgo
exec: "clang": executable file not found in $PATH
panic: exit status 2

goroutine 1 [running]:
main.main()
    /Users/jbd/src/github.com/rakyll/go2xcode/main.go:72 +0xbf1