[PATCH 1/2] Add note on MALLOC_MMAP_* environment variables

[Kalle Olavi Niemitalo]

Siddhesh Poyarekar <siddhesh@sourceware.org> writes:

> +This parameter can also be set for the process at startup by setting the
> +environment variable @code{MALLOC_MMAP_MAX_} to the desired value.

startup.texi has e.g. "@cindex @code{TZ} environment variable".
Could add similar index entries for MALLOC_MMAP_MAX_ and others.

Inconsistently, @vindex is used for the PWD, LANGUAGE, and
COREFILE environment variables.