prim_ops: fix some indentation

[lkundrak]

It upsets gcc's -Wmisleading-indentation:

  prim_ops.c: In function ‘sbb_word’:
  prim_ops.c:1780:5: warning: this ‘else’ clause does not guard... [-Wmisleading-indentation]
   1780 |     else
        |     ^~~~
  In file included from prim_ops.c:99:
  include/x86emu_int.h:76:3: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘else’
     76 |   if(COND) SET_FLAG(FLAG); else CLEAR_FLAG(FLAG)
        |   ^~
  prim_ops.c:1782:9: note: in expansion of macro ‘CONDITIONAL_SET_FLAG’
   1782 |         CONDITIONAL_SET_FLAG(res & 0x8000, F_SF);
        |         ^~~~~~~~~~~~~~~~~~~~
  prim_ops.c: In function ‘sbb_long’:
  prim_ops.c:1805:5: warning: this ‘else’ clause does not guard... [-Wmisleading-indentation]
   1805 |     else
        |     ^~~~
  include/x86emu_int.h:76:3: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘else’
     76 |   if(COND) SET_FLAG(FLAG); else CLEAR_FLAG(FLAG)
        |   ^~
  prim_ops.c:1807:9: note: in expansion of macro ‘CONDITIONAL_SET_FLAG’
   1807 |         CONDITIONAL_SET_FLAG(res & 0x80000000, F_SF);
        |         ^~~~~~~~~~~~~~~~~~~~