Graphviz aliases memory.h and malloc.h

[AstralStorm]

Graphviz is aliasing system headers memory.h and malloc.h.

This causes build failures against libc different than glibc, for example with bionic.

Additionally quite a few source files include <memory.h> while they should be using the graphviz version.

[graphviz]

I don’t know what we should do about this, but I’d like to note that according to the contents of the graphviz malloc.h, this aliasing seems to be intentional. Sorry.