As v0.4 introduced ext4-style feature flags, the on-disk format version
is unlinkely to change. Drop it from the version output to reduce
clutter. Use "gocryptfs -version -debug" to see it.
Add the Go version string because only Go 1.6 and newer have an optimized
AES-GCM implementation. This will help users to understand the performance
of their build.
This used to fail in an ugly way:
$ ./build.bash
./build.bash: line 13: go: command not found
./build.bash: line 15: [: too many arguments
./build.bash: line 20: go: command not found