This patch adds targets for printf and fprintf to the bazel build.
Additionally, it adds support for the build system to specify where
files should be written for testing purposes. This was necessary to
enable the fprintf test under bazel.
Reviewed By: sivachandra
Differential Revision: https://reviews.llvm.org/D147008
This part of the effort to make all test related pieces into the `test`
directory. This helps is excluding test related pieces in a straight
forward manner if LLVM_INCLUDE_TESTS is OFF. Future patches will also move
the MPFR wrapper and testutils into the 'test' directory.
