Reverted changes for eByteOrderHost detection, but added linux support for using <endian.h>. No files in "API" can include any LLVM header files. We must keep LLVM behind our API.
Reverted changes for eByteOrderHost detection, but added linux support for using <endian.h>. No files in "API" can include any LLVM header files. We must keep LLVM behind our API.

git-svn-id: b33bab8abb5b18c12ee100cd7761ab452d00b2b0@105892 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-lldb,llvm-mirror/lldb,llvm-mirror/lldb,apple/swift-lldb,apple/swift-lldb,llvm-mirror/lldb,apple/swift-lldb,llvm-mirror/lldb,apple/swift-lldb,apple/swift-lldb,llvm-mirror/lldb