fails with gcc15

[pgajdos]

[   12s] In file included from ../../src/pdsh/dsh.h:38,
[   12s]                  from pipecmd.c:43:
[   12s] ../../src/common/macros.h:62:16: error: cannot use keyword ‘false’ as enumeration constant
[   12s]    62 | typedef enum { false, true } bool;
[   12s]       |                ^~~~~
[   12s] ../../src/common/macros.h:62:16: note: ‘false’ is a keyword with ‘-std=c23’ onwards
[   12s] ../../src/common/macros.h:62:30: error: expected ‘;’, identifier or ‘(’ before ‘bool’
[   12s]    62 | typedef enum { false, true } bool;
[   12s]       |                              ^~~~