syscall: Drop unneeded addr variable

Otherwise it become a global variable propagated
even to files where it must has no reference to
(such as parasite code)

Symbol table '.symtab' contains 22 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
...
     4: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS parasite.c
...
    21: 000000000000b208     8 OBJECT  GLOBAL DEFAULT    3 addr

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>