Using clang++ 3.x -fsanitize

clang-runtime-checks.sh

# Clang runtime checks

## gochas
 - The compiler_rt code must be built (if compiling llvm/clang with
   cmake you need cmake > 2.8.7)
 - `-fsanitize=thread` and therefore the `tsan` symbols are not available on OS X
 - Missing `asan` symbols can be solved on OS X by doing:

```
export DYLD_INSERT_LIBRARIES=/opt/llvm2/lib/clang/3.3/lib/darwin/libclang_rt.asan_osx_dynamic.dylib
```

 - Missing `ubsan` symbols like `Symbol not found: ___ubsan_handle_sub_overflow`
   can be solved by statically linking the `libclang_rt.ubsan_osx.a` library.
 - Both the above problems should be avoidable by doing export
   `LD=clang++` and/or by ensuring that the `-fsanitize` option
   is also included in the `LINKFLAGS` as well as the `CXXFLAGS`
   but this did not work for me
 - A missing symbol like `__ZTIN10__cxxabiv117__class_type_infoE`
   can be avoided by not specifying `-fsanitize=vptr` (which is included if you do `-fsanitize=undefined`)

## build clang latest with cmake on OS X:

```sh
## docs:
 # http://clang.llvm.org/get_started.html#build
 # http://www.llvm.org/docs/CMake.html
 # http://llvm.org/docs/GettingStarted.html#getting-started-quickly-a-summary
 # http://clang.llvm.org/docs/HowToSetupToolingForLLVM.html

## requirements:
 # make sure you have cmake > 2.8.7, otherwise compiler_rt will not be compiled

svn co http://llvm.org/svn/llvm-project/llvm/trunk llvm2
cd llvm2
cd tools
svn co http://llvm.org/svn/llvm-project/cfe/trunk clang
cd clang/tools
svn co http://include-what-you-use.googlecode.com/svn/trunk/ include-what-you-use
echo 'add_subdirectory(include-what-you-use)' >> CMakeLists.txt
svn co http://llvm.org/svn/llvm-project/clang-tools-extra/trunk extra
cd ../../../
cd projects
svn co http://llvm.org/svn/llvm-project/compiler-rt/trunk compiler-rt
# cmake approach
mkdir -p build
cd build
cmake ../ -DCMAKE_BUILD_TYPE:STRING=Release \
  -DCMAKE_INSTALL_PREFIX:PATH=/opt/llvm2 \
  -DCMAKE_EXPORT_COMPILE_COMMANDS:BOOL=ON ../
make
#cp ../tools/clang/tools/scan-build/scan-build/* /opt/llvm/bin/
#cp ../tools/clang/tools/scan-view/scan-view/* /opt/llvm/bin/
```