PPAPI: Remove clang plugins from ppapi/tests/clang

ppapi/tests/clang/README

-This is a directory for Clang plugins that are designed to do analysis and/or
-manipulation of PPAPI code.  Clang is an open-source C front-end that allows
-you to parse C, C++, or Objective-C code in to an abstract syntax tree (or AST)
-for processing.  This README assumes that you are working in a check-out of
-chromium.
-
-To use these plugins, you will need to get Clang.  Clang is rapidly changing,
-so you may want to download and build it yourself.  See the instructions here:
-- http://clang.llvm.org/get_started.html
-
-To build the plugins, use the Makefile in this directory.  If you want the
-provided Makefile to work out-of-the-box, in step 2 of the instructions at the
-above URL, you should do the following:
-> mkdir ~/llvm
-> cd ~/llvm
-Now continue with the svn co command to check out llvm in ~/llvm/llvm.  If you
-choose to build llvm in another location, you can use environment variables to
-force the Makefile to find your build of clang.  See the Makefile for details.
-
-To run a plugin, use clang with the -cc1 -load and -plugin flags and an
-otherwise normal build line.  For example, to run liBPrintNamesAndSizes.so, if
-you currently build like this:
-g++ (build_options)
-Run this from the command-line instead:
-clang -cc1 -load ppapi/tests/clang/libPrintNamesAndSizes.so \
-  -plugin PrintNamesAndSizes (build_options)
-
-Plugins:
-  PrintNamesAndSizes : print_names_and_sizes.cc
-  Print information about all top-level type definitions.  You probably won't
-  need to run it by itself;  instead see generate_ppapi_size_checks.py, which
-  uses the plugin.  See print_names_and_sizes.cc for more detail on the plugin.
-
-  Example command-line:
-    python generate_ppapi_size_checks.py \
-        --ppapi-root=/usr/local/google/chrome_build/src/ppapi
-    python generate_ppapi_size_checks.py --help
-
-
-  FindAffectedInterfaces : find_affected_interfaces.cc
-  Given typenames as parameters, print out all types that are affected
-  (including function pointer types and structs containing affected function
-  pointer types) if the given type(s) change.  This is meant to be used for
-  determining what interfaces are affected by a change to a struct.
-
-  Example command-line:
-    clang -cc1 -load ppapi/tests/clang/libFindAffectedInterfaces.so \
-        -plugin FindAffectedInterfaces -I. ppapi/tests/all_includes.h \
-        -plugin-arg-FindAffectedInterfaces \
-        "struct PP_VideoCompressedDataBuffer_Dev"
-    clang -cc1 -load tests/clang/libFindAffectedInterfaces.so \
-        -plugin FindAffectedInterfaces -I../ tests/all_c_includes.h \
-        -plugin-arg-FindAffectedInterfaces \
-        "struct PP_VideoCompressedDataBuffer_Dev,struct PP_Var"
-
-(This assumes that clang is in your path and you are running the plugin from
- the ppapi subdirectory in a chrome checkout).