strdup the input of dirname, as dirname is free

strdup the input of dirname, as dirname is free
(according to the spec) to change the string in-situ,
even if glibc doesn't do it.

This avoids errors on Mac OS and Solaris.

Kill nrv2b support in CBFS (we have lzma),
slightly improve debug output in CBFS,
properly declare all functions of CBFS in the header.

Signed-off-by: Patrick Georgi <patrick.georgi@coresystems.de>
Acked-by: Uwe Hermann <uwe@hermann-uwe.de>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@4436 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1