Log Message:
Update lang/scheme48 to 1.9.2.
Patch provided by Aleksej Lebedev via PR pkg/50425 and pkgsrc-users@.

pkgsrc changes:
 o While here fix various pkglint warnings (spaces vs tabs)
 o Update DESCR to reflect current status of scheme48 and R5RS

Changes:
* 2014-04-12 (version 1.9.2)
** Bug fixes
- Some regressions with respect to integer shifts were fixed.
- Some compiler warnings were fixed.

* 2014-02-22 (version 1.9.1)
** Bug fixes
- A bug fix from SRFI 13 was imported (in `string-trim-right').
- =DESTDIR= is now used consistently in the Makefile.
- A bug in `integer->errno' was fixed. (William Vining)
- Various problems that broke the VM when compiled with Clang were
  fixed.