linux-stable v5.4.x, v5.10.x & v5.15.x fail to build with GCC 15.x

[pbrkr]

The new Yocto Project 5.3 "Whinlatter" release will use GCC 15.x. We need to request additional backports if we want to support building older kernel branches with the new Yocto Project release.

I don't think it's worth requesting the backports for Linux 5.4.x as that goes EOL in December this year. But it is worth handling this for 5.10.x & 5.15.x.

An example failue:

In file included from /mnt/build/meta-linux-mainline/master/5.4/qemux86-64/build/tmp/work/qemux86_64-poky-linux/linux-stable/5.4.300/git/include/uapi/linux/posix_types.h:5,
                 from /mnt/build/meta-linux-mainline/master/5.4/qemux86-64/build/tmp/work/qemux86_64-poky-linux/linux-stable/5.4.300/git/include/uapi/linux/types.h:14,
                 from /mnt/build/meta-linux-mainline/master/5.4/qemux86-64/build/tmp/work/qemux86_64-poky-linux/linux-stable/5.4.300/git/include/linux/compiler.h:249,
                 from /mnt/build/meta-linux-mainline/master/5.4/qemux86-64/build/tmp/work/qemux86_64-poky-linux/linux-stable/5.4.300/git/include/linux/init.h:5,
                 from /mnt/build/meta-linux-mainline/master/5.4/qemux86-64/build/tmp/work/qemux86_64-poky-linux/linux-stable/5.4.300/git/include/linux/efi.h:15,
                 from /mnt/build/meta-linux-mainline/master/5.4/qemux86-64/build/tmp/work/qemux86_64-poky-linux/linux-stable/5.4.300/git/drivers/firmware/efi/libstub/efi-stub-helper.c:10:
/mnt/build/meta-linux-mainline/master/5.4/qemux86-64/build/tmp/work/qemux86_64-poky-linux/linux-stable/5.4.300/git/include/linux/stddef.h:11:9: error: cannot use keyword 'false' as enumeration constant
   11 |         false   = 0,
      |         ^~~~~
/mnt/build/meta-linux-mainline/master/5.4/qemux86-64/build/tmp/work/qemux86_64-poky-linux/linux-stable/5.4.300/git/include/linux/stddef.h:11:9: note: 'false' is a keyword with '-std=c23' onwards
In file included from /mnt/build/meta-linux-mainline/master/5.4/qemux86-64/build/tmp/work/qemux86_64-poky-linux/linux-stable/5.4.300/git/arch/x86/include/asm/alternative.h:7,
                 from /mnt/build/meta-linux-mainline/master/5.4/qemux86-64/build/tmp/work/qemux86_64-poky-linux/linux-stable/5.4.300/git/arch/x86/include/asm/barrier.h:5,
                 from /mnt/build/meta-linux-mainline/master/5.4/qemux86-64/build/tmp/work/qemux86_64-poky-linux/linux-stable/5.4.300/git/include/linux/compiler.h:325:
/mnt/build/meta-linux-mainline/master/5.4/qemux86-64/build/tmp/work/qemux86_64-poky-linux/linux-stable/5.4.300/git/include/linux/types.h:30:33: error: 'bool' cannot be defined via 'typedef'
   30 | typedef _Bool                   bool;
      |                                 ^~~~
/mnt/build/meta-linux-mainline/master/5.4/qemux86-64/build/tmp/work/qemux86_64-poky-linux/linux-stable/5.4.300/git/include/linux/types.h:30:33: note: 'bool' is a keyword with '-std=c23' onwards
/mnt/build/meta-linux-mainline/master/5.4/qemux86-64/build/tmp/work/qemux86_64-poky-linux/linux-stable/5.4.300/git/include/linux/types.h:30:1: warning: useless type name in empty declaration
   30 | typedef _Bool                   bool;
      | ^~~~~~~