Add support for building Xcode project files from GYP files

build/README.txt

 This directory contains the V8 GYP files used to generate actual project files
 for different build systems.
 
 This is currently work in progress but this is expected to replace the SCons
 based build system.
 
 To use this a checkout of GYP is needed inside this directory. From the root of
 the V8 project do the following:
 
 $ svn co http://gyp.googlecode.com/svn/trunk build/gyp
 
+Note for the command lines below that Debug is the default configuration,
+so specifying that on the command lines is not required.
+
+
 To generate Makefiles and build 32-bit version on Linux:
 --------------------------------------------------------
 
-$ GYP_DEFINES=target_arch=ia32 build/gyp_v8
-$ make
+$ build/gyp_v8 -D target_arch=ia32
+$ make BUILDTYPE=Debug
+$ out/Debug/shell
+$ make BUILDTYPE=Release
+$ out/Release/shell
 
 To generate Makefiles and build 64-bit version on Linux:
 --------------------------------------------------------
 
-$ GYP_DEFINES=target_arch=x64 build/gyp_v8
-$ make
+$ build/gyp_v8 -D target_arch=x64
+$ make BUILDTYPE=Debug
+$ out/Debug/shell
+$ make BUILDTYPE=Release
+$ out/Release/shell
 
 To generate Makefiles and build for the arm simulator on Linux:
 ---------------------------------------------------------------
 
-$ build/gyp_v8 -I build/arm.gypi
-$ make
+$ build/gyp_v8 -I build/armu.gypi
+$ make BUILDTYPE=Debug
+$ out/Debug/shell
+$ make BUILDTYPE=Release
+$ out/Release/shell
+
+
+To generate Xcode project files on Mac OS:
+------------------------------------------
+
+$ build/gyp_v8 -D target_arch=ia32
+$ xcodebuild -project build/all.xcodeproj -configuration Debug
+$ samples/build/Debug/shell
+$ xcodebuild -project build/all.xcodeproj -configuration Release
+$ samples/build/Release/shell
+
 
 To generate Visual Studio solution and project files on Windows:
 ----------------------------------------------------------------
 
 On Windows an additional third party component is required. This is cygwin in
 the same version as is used by the Chromium project. This can be checked out
 from the Chromium repository. From the root of the V8 project do the following:
 
 > svn co http://src.chromium.org/svn/trunk/deps/third_party/cygwin@66844 third_party/cygwin
 
 To run GYP Python is required and it is reccomended to use the same version as
 is used by the Chromium project. This can also be checked out from the Chromium
 repository. From the root of the V8 project do the following:
 
 > svn co http://src.chromium.org/svn/trunk/tools/third_party/python_26@70627 third_party/python_26
 
 Now generate Visual Studio solution and project files:
 
 > third_party\python_26\python build/gyp_v8 -D target_arch=ia32
 
 Now open build\All.sln in Visual Studio.