Merge branch 'jk/write-in-full-fix'

Many codepaths did not diagnose write failures correctly when disks
go full, due to their misuse of write_in_full() helper function,
which have been corrected.

* jk/write-in-full-fix:
  read_pack_header: handle signed/unsigned comparison in read result
  config: flip return value of store_write_*()
  notes-merge: use ssize_t for write_in_full() return value
  pkt-line: check write_in_full() errors against "< 0"
  convert less-trivial versions of "write_in_full() != len"
  avoid "write_in_full(fd, buf, len) != len" pattern
  get-tar-commit-id: check write_in_full() return against 0
  config: avoid "write_in_full(fd, buf, len) < len" pattern

refs.c

@@ -609,7 +609,7 @@ static int write_pseudoref(const char *pseudoref, const unsigned char *sha1,
 		}
 	}
 
-	if (write_in_full(fd, buf.buf, buf.len) != buf.len) {
+	if (write_in_full(fd, buf.buf, buf.len) < 0) {
 		strbuf_addf(err, "could not write to '%s'", filename);
 		rollback_lock_file(&lock);
 		goto done;