nvram: Allow zero-terminated output
nvram: Allow zero-terminated output

Currently, there's no way to accurately parse the outout of nvram
--print-config: properties may contain a newline, which we can't
distinguish from the end-of-property token.

This change adds a --zero/-0 option to terminate config pairs with a
NUL character instead.

Signed-off-by: Jeremy Kerr <68a658b44bbaefab3ef5cd231967195fc0ff9d69@ozlabs.org>

leitao/powerpc-ibm-utils-debian,tyreld/powerpc-utils,kamalesh-babulal/powerpc-utils,tyreld/powerpc-utils,mdroth/powerpc-utils,shenki/powerpc-utils,mdroth/powerpc-utils,tyreld/powerpc-utils,kamalesh-babulal/powerpc-utils,shenki/powerpc-utils,leitao/powerpc-ibm-utils-debian,leitao/powerpc-ibm-utils-debian,mdroth/powerpc-utils,shenki/powerpc-utils,kamalesh-babulal/powerpc-utils