142288 broke the build:

Linking CXX executable ../../bin/llvm-as
../../lib/libLLVMAsmParser.a(LLParser.cpp.o):/home/espindola/llvm/llvm/lib/AsmParser/LLParser.cpp:function llvm::LLParser::ParseTargetDefinition(): error: undefined reference to 'llvm::TargetData::parseSpecifier(llvm::StringRef, llvm::TargetData*)'
clang-3: error: linker command failed with exit code 1 (use -v to see invocation)

Revert "Validate target data layout strings."

This reverts commit 599d2d4c25d3aee63a21d9c67a88cd43bd971b7e.

llvm-svn: 142296