add build notes for using clang

Building-For-Linux.md

@@ -28,6 +28,8 @@ The `--recursive` option automatically clones the required Git submodules too.
 
 ### Building Citra:
 
+**Using gcc:**
+
 ```
 mkdir build && cd build
 cmake ..
@@ -36,6 +38,19 @@ sudo make install (currently doesn't work, needs to be fixed)
 ```
 Optionally, you can use "cmake -i .." to adjust various options (e.g. disable the Qt GUI).
 
+**Using clang:**
+
+Note: It is important you use libc++ vs. , otherwise your build will likely fail. libc++ is not 100% complete on GNU/Linux, but works well for this build. The libstdc++ std::string is a different data structure than the libc++ std::string. See: [LLVLM.org](https://llvm.org/svn/llvm-project/www-releases/trunk/3.8.0/projects/libcxx/docs/UsingLibcxx.html). If libc+ is not used, some warnings are treated as errors. Using clang is only really recommended for users not using GCC >= 5. Also see [Clang Comparison](http://clang.llvm.org/comparison.html).
+
+```
+mkdir build && cd build
+cmake  -DCMAKE_CXX_COMPILER=clang++-3.8 \
+	-DCMAKE_C_COMPILER=clang-3.8 \
+	-DCMAKE_CXX_FLAGS="-O2 -g -stdlib=libc++"  ..
+make
+sudo make install (currently doesn't work, needs to be fixed)
+```
+
 ### Building Citra (Optimized):
 
 ```