[lsan] Build standalone LSan with -fno-rtti.

Fix issue where C code could not be built with -fsanitize=leak.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@189010 91177308-0d34-0410-b5e6-96231b3b80d8
[lsan] Follow-up to r189010 - do the same in Makefile build.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@189011 91177308-0d34-0410-b5e6-96231b3b80d8
[lsan] Add a stress test.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@189012 91177308-0d34-0410-b5e6-96231b3b80d8