Improve realloc on fixed buffer allocator (#1238)
Improve realloc on fixed buffer allocator (#1238)

* Add test to check re-use of memory

* Check if realloc has to reallocate the last allocated memory block.
If so extend that block instead of allocating a new one.

* Also check if the realloc actually preserves the data.

Dimenus/zig,raulgrell/zig,raulgrell/zig,zig-lang/zig,zig-lang/zig,raulgrell/zig,Dimenus/zig,zig-lang/zig,Dimenus/zig,andrewrk/zig,andrewrk/zig,raulgrell/zig,raulgrell/zig