sfio: correct misleading indentation in REINIT macro definition

sfio: correct misleading indentation in REINIT macro definition

Fixes errors like this when building with CMake (which uses -Wall,
-Wextra and -Werror) on Ubuntu 21.10 with gcc 11.2.0.

../lib/sfio/sfdisc.c:114:25: error: this ‘for’ clause does not guard... [-Werror=misleading-indentation]
  114 |                 {       for(d = f->disc; d && !d->iof; d = d->disc) ; \
      |                         ^~~
../lib/sfio/sfdisc.c:119:9: note: in expansion of macro ‘REINIT’
  119 |         REINIT(oreadf, readf, Sfread_f);
      |         ^~~~~~
../lib/sfio/sfdisc.c:115:25: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the ‘for’
  115 |                         if(DISCF(d,iof,type) != oiof) \
      |                         ^~
../lib/sfio/sfdisc.c:119:9: note: in expansion of macro ‘REINIT’
  119 |         REINIT(oreadf, readf, Sfread_f);
      |         ^~~~~~