glibc_malloc_overhead

[Eli Zaretskii]

Re this change:

  -    initial_malloc_max = (1 << 16) - 1 - XMALLOC_OVERRUN_CHECK_OVERHEAD,
  +    glibc_malloc_overhead = 3 * sizeof (size_t) - 1,
  +    initial_malloc_max =
  +      (1 << 16) - 1 - glibc_malloc_overhead - XMALLOC_OVERRUN_CHECK_OVERHEAD,
       charset_table_size_init = initial_malloc_max / sizeof (struct charset)
     };
 
How stable can we expect the value of glibc_malloc_overhead to be?
What if the glibc developers decide to change it whenever they see
fit?

In any case, I'd suggest to only account for this overhead if glibc is
being used.  No need to "punish" other builds, especially if they
don't use mmap at all.