Remove references to svn version control.

docs/getting_started.md

 # Getting Started
 
 How to get and build the libyuv code.
 
 ## Pre-requisites
 
 You'll need to have depot tools installed: https://www.chromium.org/developers/how-tos/install-depot-tools
 Refer to chromium instructions for each platform for other prerequisites.
 
 ## Getting the Code
@@ skipping 66 matching lines @@
     call python gyp_libyuv -fninja -G msvs_version=2013
     ninja -j7 -C out\Release
     ninja -j7 -C out\Debug
 
     set GYP_DEFINES=target_arch=x64
     call python gyp_libyuv -fninja -G msvs_version=2013
     ninja -C out\Debug_x64
     ninja -C out\Release_x64
 
 #### Building with clangcl
-    set GYP_DEFINES=clang=1 target_arch=ia32 libyuv_enable_svn=1
-    set LLVM_REPO_URL=svn://svn.chromium.org/llvm-project
+    set GYP_DEFINES=clang=1 target_arch=ia32
     call python tools\clang\scripts\update.py
     call python gyp_libyuv -fninja libyuv_test.gyp
     ninja -C out\Debug
     ninja -C out\Release
 
 ### OSX
 
 Clang 64 bit shown. Remove `clang=1` for GCC and change x64 to ia32 for 32 bit.
 
     GYP_DEFINES="clang=1 target_arch=x64" ./gyp_libyuv
@@ skipping 323 matching lines @@
     git checkout -b mycl -t origin/master
     git pull
     <edit files>
     git add -u
     git commit -m "my change"
     git cl lint
     git cl try
     git cl upload -r a-reviewer@chomium.org -s
     <once approved..>
     git cl land