Forward Mode CallInst known functions (rust-lang#299)

* forward mode call inst known functions

* add tests

* fix tests

* fix julia.write_barrier

* fix _ZSt29_Rb_tree_insert_and_rebalancebPSt18_Rb_tree_

* fix __dynamic_cast

* Alloc / dealloc

* fix else condition

* fix pointer for free and add runtime check to prevent double free.

* posix_memalign

Author: tgymnich