Analyse following RPM build log snippet. Describe contents accurately, without speculation or suggestions for resolution.            
Your analysis must be as concise as possible, while keeping relevant information intact.
Snippet: 
In file included from ./include/uapi/linux/posix_types.h:5,
                 from ./include/uapi/linux/types.h:14,
                 from ./include/linux/types.h:6,
                 from ./include/linux/kasan-checks.h:5,
                 from ./include/asm-generic/rwonce.h:26,
                 from ./arch/x86/include/generated/asm/rwonce.h:1,
                 from ./include/linux/compiler.h:314,
                 from ./include/linux/build_bug.h:5,
                 from ./include/linux/init.h:5,
                 from ./include/linux/efi.h:15,
                 from drivers/firmware/efi/libstub/efi-stub-helper.c:12:
./include/linux/stddef.h:11:9: error: cannot use keyword âfalseâ as enumeration constant
   11 |         false   = 0,
      |         ^~~~~
./include/linux/stddef.h:11:9: note: âfalseâ is a keyword with â-std=c23â onwards
The code is not C23 compliant. The keyword 'false' is used in enumeration as a constant.