For this ensure that all bss sections are merged.

all_video module does not have any code or data and exists solely for
.moddeps section to pull in dependencies. This makes all symbols unneeded.

While in current binutils (last released version as of this commit is 2.26)
``strip --strip-unneeded'' unintentionally adds section symbols for each
existing section, this behavior was considered a bug and changed in commit
14f2c699ddca1e2f706342dffc59a6c7e23e844c to completely strip symbol table
in this case.

Older binutils (verified with 2.17) and some other toolchains (at least
elftoolchain r3223M), both used in FreeBSD, remove symbol table in all_video
as well.

Relax run-time check and do not return error for modules without symbol table.
Add additional checks to module verifier to make sure such modules

a) have non-empty .moddeps section. Without either externally visible symbols
or .moddeps modules are completely useless and should not be built.

b) do not have any relocations.

Closes: 46986

v2: add run-time check for empty symbol table if relocations are present as
    suggested by Vladimir.

If root filesystem is multidev btrfs, do not attempt to pass all devices as
kernel root= argument. This results in splitting command line in GRUB due to
embedded newline and even if we managed to quote it, kernel does not know how
to interpret it anyway. Multidev btrfs requires user space device scanning,
so passing single device would not work too.

This still respects user settings GRUB_DISABLE_LINUX_UUID. Not sure what we
should do in this case.

Closes: 45709

Found by: Coverity scan.
CID: 73783

This matches behavior of "nativedisk" command.

Reported and tested by Smith Henry <sh37092@gmail.com>

Found by: Coverity scan.
CID: 73737

Check return value of grub_guess_root_devices

Found by: Coverity scan.
CID: 73638, 73751

Found by: Coverity scan.
CID: 73691, 73717

is_part cannot be non-zero at this point.

Found by: Coveruty scan.
CID: 73838

Found by: Coverity scan.
CID: 73686

Found by: Coverity scan.
CID: 73783

Add helper grub_util_free_path_list and use it where appropriate.

Found by: Coverity scan.
CID: 73727

Found by: Coverity scan.
CID: 73680, 73715

Found by: Coverity scan.
CID: 156533, 156532

So that we can use it in grub-emu as well as utils.

clang as incomplete mcmodel=large support. As we don't currently need full
mcmodel=large support for sparc64, relax those checks.

Check that they point to the same module, so will end up in the same
chunk of memory.

Currently only Windows gets distinguished icons, everything else is displayed
using the same generic one. Add additional --class based on os-prober returned
label, which usually is expected to match primary distribution name.

Also use it for Windows as well - chainloader prober may actually return
different strings (Windows, MS-DOS, Windows9xME).

Reported by: Thomas Schmitt