Fix linkage error on ProgramPoint's dump method.

Currently, ProgramPoint::dump calls the out-of-line function ProgramPoint::print. This causes
libraries which include ProgramPoint.h to become dependent on libclangAnalysis, which in turn
causes missing symbol link error when building with -DBUILD_SHARED_LIBS=ON -DLLVM_ENABLE_MODULES=ON.

The breakage was introduced in r343160.

This patch fixes the issues by moving ProgramPoint::dump's declaration out of line.

llvm-svn: 343420