Replacement of std::malloc

[mitinarseny]

Following functions are needed to replace std::malloc:

• malloc
• free
• calloc
• realloc
• aligned_alloc
• malloc_usable_size
• memalign
• posix_memalign
• pvalloc
• valloc

Additionally, we should check if it is necessary to overload C++ new and delete operators (#4).

Other programs that are dynamically linked to libstdc++ may be overrode to link with our custom malloc implementation with help of dynamic override.