Merge branch 'signed-seek' into 'master'

change seek sig to match posix - signed pos and result

See merge request !45
3 jobs for master in 1 minute and 56 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #27881
build:linux

00:00:45

passed #27882
build:redox

00:00:43

 
  Test
failed #27883
test:redox

00:01:10

 
Name Stage Failure
failed
test:redox Test
redoxer: copying 'libstdc++.so.6.0.25' to '/lib'
redoxer: replacing '/builds/redox-os/syscall/target/x86_64-unknown-redox/debug/deps/syscall-28222d485c747e4c' with '/root/target/x86_64-unknown-redox/debug/deps/syscall-28222d485c747e4c' in arguments
redoxer: copying '.' to '/root'
qemu-system-x86_64: cannot set up guest memory 'pc.ram': Cannot allocate memory

## redoxer (failure, qemu exit status ExitStatus(ExitStatus(256)) ##
error: test failed, to rerun pass '--lib'
redoxer cargo: exit code: 2
ERROR: Job failed: exit code 1