bash: Disable custom memory allocator

Bash is failing trying to allocate memory [1] using the custom
memory allocator if we disable it the issue is fixed.

The major distributions also disabled by default [2], so we
don't have a good reason to use it.

The underlying issue is due to bash’s malloc using brk() calls
to allocate memory, which fail when address randomization is
enabled in kernel. sbrk() based custom allocators are obsolete.
There may be some performance impact of this however correctness
is more important.

[YOCTO #8452]

[1] https://bugzilla.yoctoproject.org/show_bug.cgi?id=8452#c0
[2] https://bugzilla.yoctoproject.org/show_bug.cgi?id=8452#c5



(From OE-Core master rev: e42d8eff)

Signed-off-by: Aníbal Limón <anibal.limon@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Joshua Lock <joshua.lock@collabora.co.uk>