Fixes build when running make -k check:

* Fixes Broken Test in BuildEngine for 4.0 and 3.5
* Fixes build for Mono.Debugger.Soft not in 4_5 profile
* Fixes build for NET_4_0 profile (CustomAttributes and HasDefaultValue)
Merge pull request #749 from head-thrash/master

Fixes build when running `make -k check`