some comment spelling fixes

src/mdlib.c

@@ -232,7 +232,7 @@ static struct soundlib_information soundlib_opts[] = {
  * Use this to explicitly mask out features during version checks.
  *
  * ZEROCOMP, RLECOMP, and ZLIB_COMP describe compression features
- * that the port/plaform which wrote the savefile was capable of
+ * that the port/platform which wrote the savefile was capable of
  * dealing with. Don't reject a savefile just because the port
  * reading the savefile doesn't match on all/some of them.
  * The actual compression features used to produce the savefile are