lib/devel/buildenv: add @sections
lib/devel/kernel-comp: kcomp_gen_install_makefile()

Generates a Makefile for installing the content of kcomp tarball.
scripts/devel/kcomp: some updates

* kernel_apply_patchsets(): don't run modules_prepare when building a static
  kernel
* apply user-defined patch sets ($USER_PATCHSETS + kcomp_patchset_<name>())
* function for listing all official kernel releases (git.ko.o)
* git: accept arbitrary URIs in KERNEL_SRC (prefixed with "git=")
* fix minor doc/message typos
* set TARGET_FILENAME, TARGET_NAME, (guessed) TARGET_VERSION before
  loading the target config file.
* add KERNEL_SRC_URI, KERNEL_SRC_VERSION variables
* "tarball" kernels: automatically fetch the source if possible/required
* add (KCOMP_)DISTDIR variable
* generate a Makefile and pack it into the tarball if KERNEL_GEN_MAKEFILE
  is true (defaults to "n"). The Makefile can be used to (un-)install
  the kernel/its modules and to get basic information (version, ...).

Notes: "tarball" target configs still need to set KERNEL_SRC
scripts/devel/kcomp.sh: http_fetch_file()
lib/fs: chdir

"cd <dir> || die".
scripts/devel/kcomp: --dist, fixup
lib/scriptinfo: set vars in module_init_vars
lib/devel/buildenv: fix comment
lib/initramfs: fixup, logging, execute hooks

* log more (and log some messages to kmsg)
* liram: add possibility to execute user scripts
  ($NEWROOT/initramfs-config/scripts/<name>),
  either directly or in a newroot chroot (.chroot file suffix)
  Whether this feature is used or not depends on the liram layout(!).
liram: add 'stage3' layout

Boots into a gentoo stage3/stage4 tarball. An optional, but highly recommended
stage3-overlay tarball can be used to provide additional files, e.g. network
config or a hook for setting the root password (usually required for stage3).
minor fixup
lib/fs/symlinkdb: fix symlink_db_create_new_symlink()

$link is not set.