The dynamic arrays implemented by the attached patch are intended as a 
simplified, type-safe replacement for obstacks, and can be used to 
replace custom array management with an on-stack initial buffer and an 
exponential resizing policy using realloc.

Test coverage should be reasonable complete, including allocation error 
testing.  For the __libc_fatal testing, I had to add some support machinery.

The __check_mul_overflow_size_t function should go into the 
<malloc-private.h> header once it exists (probably without the two 
leading underscore).

Thanks,
Florian