Fix msan/tests/msan_test.cpp due to -Wbitwise-instead-of-logical

The LE Power sanitizer bot fails when testing standalone compiler-rt due to
an MSAN test warning introduced by -Wbitwise-instead-of-logical. As this option
along with -Werror is enabled on the bot, the test failure occurs.
This patch updates msan_test.cpp to fix the warning introduced by the
-Wbitwise-instead-of-logical.