fix displaying sector number when above 2^31
1.2.13

- fix displaying sector number when above 2^31
- fix potential file descriptor leak (thanks to Rich Burridge)
- add DESTDIR support to the makefiles
- preprocessor flags should use CPPFLAGS, not CFLAGS
- fix a small issue in mymemmem/mymemrmem when HAVE_MEMMEM/HAVE_MEMRMEM is not defined