This patch adds a parallel set of APIs to the domain builders to
allow images and ramdisks to be passed via buffer, rather than
via file.  This allows usage of the underlying domain building
routines in "file-challenged" enviroments.

Specifically,  xc_linux_build_mem is the buffer oriented version
of the file-oriented xc_linux_build.  Likewise, xc_hvm_build_mem
is the buffer oriented analog of the file based xc_hvm_build.

This patch also implements a suggestion by Mark Williamson to have
the internal APIs always directly use uncompressed buffers.

-b


Signed-off-by: Ben Thomas (bthomas@virtualiron.com)