Ah/branch backend libs

[a-hamitouche]

Proposed Interface for enhanced backend usage of SIMD acceleration and overhead reduction. Implementation of a mechanism to allow dynamic loading of backends as shared objects.

Modifications

• Use of Interflop interface to enable dynamic loading of backend and make their build independent of PENE's build.
• Use of vectorial interface to improve instrumentation/reduce instrumentation overhead
• Proposition of simple implementation of arpg library to deal with backend's arguments

Limits

• As of now, quad precision isn't supported by Pin CRT. One should provide an implementation
• Dynamic loading is guaranteed to work on Linux only. For Windows compatibility, one should deal with windows and linux C headers.

[CLAassistant]

All committers have signed the CLA.