Remove OnDiskHashTable.h, since it's been moved to llvm

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@206637 91177308-0d34-0410-b5e6-96231b3b80d8

• include/clang/Basic/OnDiskHashTable.h[Deleted - diff]
• include/clang/Serialization/ASTReader.h[diff]
• include/clang/Serialization/Module.h[diff]
• lib/Frontend/CacheTokens.cpp[diff]
• lib/Lex/PTHLexer.cpp[diff]
• lib/Serialization/ASTReaderInternals.h[diff]
• lib/Serialization/ASTWriter.cpp[diff]
• lib/Serialization/GlobalModuleIndex.cpp[diff]