1. It turns out that the crosstest scripts mix different versions of
clang - build_pnacl_ir.py uses pnacl-clang from the NaCl SDK for the
tests, while crosstest.py uses clang/clang++ from LLVM_BIN_PATH for
the driver.  The SDK has been updated to use a different version of
the standard library, and now there is a mismatch as to whether int8_t
is typedef'd to 'char' or 'signed char', leading to name mangling
mismatches.  (char, signed char, and unsigned char are distinct
types.)  We deal with this by using myint8_t which is explicitly
defined as signed char.

2. Some ugly function pointer casting in test_arith_main.cpp is fixed/removed.

3. std::endl is replaced with "\n".

4. License text is added to tests that were touched by the above items.

BUG= none
R=wala@chromium.org

Review URL: https://codereview.chromium.org/435353002