more modeline errata (#1019)

Somehow or another, I previously had missed `BUILD.mk` files.

In the process I found a few straggler cases where the modeline was
different from the file, including one very involved manual fix where a
file had been treated like it was ts=2 and ts=8 on separate occasions.

The commit history in the PR shows the gory details; the BUILD.mk was
automated, everything else was mostly manual.

libc/stdio/clearerr_unlocked.c

@@ -23,7 +23,7 @@
  * Clears eof and error state indicators on stream.
  *
  * @param f is file object stream pointer
- * @see	clearerr()
+ * @see clearerr()
  */
 void clearerr_unlocked(FILE *f) {
   f->state = 0;