added postmain zcall
Merge pull request #17 from YaroslavLitvinov/master

added postmain zcall
zcall 'rename' added, implementation moved into zerovm/zrt
folowing zcalls supported: readlink, symlink, statvfs;
Merge pull request #18 from YaroslavLitvinov/master

extended filesystem syscalls list
Merge pull request #19 from YaroslavLitvinov/dev

Dev
__ZRT_HOST TLS enabled; added configure into .gitignore

x86_64 TLS enabled, thus nacl-tls code disabled;
errno, h_errno TLS variables converted to generic
for __ZRT_HOST 64bit datatypes are supported
preinit zcall added; mainly for __ZRT_HOST
__ZRT_HOST support: pagesize=4K is hardcoded, it's the same as used on ubuntu linux
configure option --with-zrt extended with value 'forhost'

__ZRT_HOST support added into configure, --with-zrt=forhost must be
used when building for host;