Guard print() functions only used by dump() functions.

Summary:
Since  r293359, most dump() function are only defined when
`!defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)` holds. print() functions
only used by dump() functions are now unused in release builds,
generating lots of warnings. This patch only defines some print()
functions if they are used.

Reviewers: MatzeB

Reviewed By: MatzeB

Subscribers: arsenm, mzolotukhin, nhaehnle, llvm-commits

Differential Revision: https://reviews.llvm.org/D35949

llvm-svn: 309553