grub: fix several CVEs in grub 2.04

grub: fix several CVEs in grub 2.04

Backport patches from https://git.savannah.gnu.org/git/grub.git
to fix some CVEs. Here is the list.

CVE-2020-14308:
0001-calloc-Make-sure-we-always-have-an-overflow-checking.patch
0002-lvm-Add-LVM-cache-logical-volume-handling.patch
0003-calloc-Use-calloc-at-most-places.patch

CVE-2020-14309, CVE-2020-14310, CVE-2020-14311:
0004-safemath-Add-some-arithmetic-primitives-that-check-f.patch
0005-malloc-Use-overflow-checking-primitives-where-we-do-.patch

CVE-2020-15706:
0006-script-Remove-unused-fields-from-grub_script_functio.patch
0007-script-Avoid-a-use-after-free-when-redefining-a-func.patch

CVE-2020-15707:
0008-linux-Fix-integer-overflows-in-initrd-size-handling.patch

Signed-off-by: Yongxin Liu <yongxin.liu@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>