[PGO] Instrument only base constructors and destructors.

Constructors and destructors may be represented by several functions
in IR. Only base structors correspond to source code, others are
small pieces of code and eventually call the base variant. In this
case instrumentation of non-base structors has little sense, this
fix remove it. Now profile data of a declaration corresponds to
exactly one function in IR, it agrees with the current logic of the
profile data loading.

This change fixes PR24996.

Differential Revision: http://reviews.llvm.org/D15158

llvm-svn: 254876