Things like error messages (e.g in the io pkg) are actually allocated
when init() is executed. Unless we trigger a call to init(), values like
this will be nil causing various problems when we try to use functions
from the stdlib.
According to the ELF runtime handling of TLS document, the x86-64 arch
uses the same TLS handling variant (GNU) as the IA-32 ABI with the
exception that pointers are 8-byte wide and that the gs register is
swapped with fs. fs:0x0 points to the TCB; TLS variables are located
before it and are accessed using negative offsets from the TCB pointer.
In the Go case the G struct is accessed at fs:-0x8.
For more detauls see: https://www.akkadia.org/drepper/tls.pdf
By setting up pwd as a Go workspace, we can trim import paths from
something like "github.com/achilleasa/gopher-os/kernel" to just
"kernel".
These changes make forking easier and also allows us to move the code to
a different git hosting provider without having to rewrite the imports.
