Fix for GCC15 / C23 build failure

[Pavel Cahyna]

Hello,

I have encountered a build failure with GCC 15, due to its adoption of
C23 as the default C language version. C23 has 'bool' (and 'true',
'false', and others) as keyword, thus it is not legal to declare 'bool'
in the code, see https://gcc.gnu.org/gcc-15/porting_to.html#c23-new-keywords

Fortunately in FreeIPMI, bool is not used as a name of a type, only as a
local variable name, so there are no ABI concerns and the fix is trivial
- patch attached. I can make a PR on GitHub / freeipmi-mirror if that's
preferred.

Best regards, Pavel

c23.patch
Description: Text document