* Removed gtest-all.cc; .cc files including other .cc files is weird

* Removed gtest-all.cc; .cc files including other .cc files is weird
* Removed gtest_main.cc: we have our own main() elsewhere
* Simplified the Makefile as we don't need SOURCES

* Moved the internal header to gtest/internal/
* Simplified the Makefile to remove -I param to CPP.Flags

* Updated README.LLVM with all the steps I took to massage GTest to
  work in LLVM so far

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@61540 91177308-0d34-0410-b5e6-96231b3b80d8