autoconf help needed

[Steve Kargl]

I'm currently writing gfortran intrinsic procedures to
achieve backwards compatibility with g77.  I know very
little about autoconf (and friends), so I'm seeking advice.

I need to test that struct stat has the 3 members
st_blksize, st_rdev, and st_blocks.  I know my
code needs for example

#if HAVE_ST_BLKSIZE
  sarray[11] = buf.st_blksize;
#else
  sarray[11] = -1;
#endif

but I don't know how to make configure properly set
HAVE_ST_BLKSIZE.

-- 
Steve