[docs] Stop trying to parse the ThinLTO summary IR fragments with the `llvm` syntax in Sphinx. This appears to just fail and create errors on the docs buildbot.
[docs] Stop trying to parse the ThinLTO summary IR fragments with the
`llvm` syntax in Sphinx. This appears to just fail and create errors on
the docs buildbot.

git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@338997 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,apple/swift-llvm