exterr: Fix build with GCC on 32-bit architectures

Use an intermediate uintptr_t cast to avoid casting a uint64_t value
directly to void * on 32-bit platforms (including lib32 builds).

lib/libc/gen/uexterr_format.c: In function 'uexterr_format_msg':
lib/libc/gen/uexterr_format.c:248:35: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast]
  248 |                         PFMT(fmt, (void *)ARG(nextarg));
      |                                   ^
lib/libc/gen/uexterr_format.c:144:47: note: in definition of macro 'PFMT'
  144 |                 psz = snprintf(buf, bufsz, f, a);                       \
      |                                               ^

Reported by:	GCC 15
Fixes:		2f024a7cfddd ("exterr: relax format restrictions")

0 files changed, 0 insertions, 0 deletions