Update 'Getting Started' to suggest using GCC 4.2 or higher (or Clang).  There is no reason to support older versions of GCC.
Update 'Getting Started' to suggest using GCC 4.2 or higher (or Clang).  There is no reason to support older versions of GCC.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@143366 91177308-0d34-0410-b5e6-96231b3b80d8

dslab-epfl/asap,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,llvm-mirror/llvm,dslab-epfl/asap,llvm-mirror/llvm,chubbymaggie/asap,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,dslab-epfl/asap,chubbymaggie/asap,GPUOpen-Drivers/llvm,llvm-mirror/llvm,chubbymaggie/asap,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,dslab-epfl/asap,dslab-epfl/asap,GPUOpen-Drivers/llvm,chubbymaggie/asap,chubbymaggie/asap,chubbymaggie/asap,dslab-epfl/asap,dslab-epfl/asap,llvm-mirror/llvm,llvm-mirror/llvm,apple/swift-llvm,apple/swift-llvm