Moves gvm inside gstate. This will make it easier to move attributes
inside gvm while keeping gambit functionnal. It should then be easy to
move it out.

Changes to be committed:
	modified:   include/gambit.h.in
Adds a ___USE_SMP definition which enables the access of os_*_structs
from a gvm.

Adds pointer to os_*_structs in gvm_struct.

 On branch para
 Changes committed:
    modified:   include/gambit.h.in
    modified:   lib/os_base.c
    modified:   lib/os_dyn.c
    modified:   lib/os_files.c
    modified:   lib/os_io.c
    modified:   lib/os_shell.c
    modified:   lib/os_time.c
    modified:   lib/os_tty.c