fix CMake: use own TestMain instead of gtest_main

Before, we would use gtest_main as provided by either LLVM or Google
Test itself; the TestMain.cpp was ignored (contrary to its source code
comment). In newer versions of Google Test (1.8.1+), gtest_main uses
`__FILE__` for its "Running main() from" line, but llvm-lit (which we
use to invoke unit tests) currently matches exactly "Running main()
from gtest_main.cc" for determining whether to skip this line. This
results in spurious "tests" that will be shown as unresolved.

0 files changed, 0 insertions, 0 deletions