[llvm] Remove "using support::endianness;" (NFC)

Now that llvm::support::endianness has been renamed to
llvm::endianness, we can directly get endianness from the llvm
namespace.  We don't need to go through support.

Author: kazutakahirata

llvm/include/llvm/Object/ELFTypes.h

@@ -24,8 +24,6 @@
 namespace llvm {
 namespace object {
 
-using support::endianness;
-
 template <class ELFT> struct Elf_Ehdr_Impl;
 template <class ELFT> struct Elf_Shdr_Impl;
 template <class ELFT> struct Elf_Sym_Impl;

llvm/lib/DebugInfo/BTF/BTFParser.cpp

@@ -204,7 +204,6 @@ const BTF::CommonType VoidTypeInst = {0, BTF::BTF_KIND_UNKN << 24, {0}};
 Error BTFParser::parseTypesInfo(ParseContext &Ctx, uint64_t TypesInfoStart,
                                 StringRef RawData) {
   using support::big;
-  using support::endianness;
   using support::little;
   using support::endian::byte_swap;
 

llvm/lib/Support/BinaryStreamReader.cpp

@@ -13,7 +13,6 @@
 #include "llvm/Support/LEB128.h"
 
 using namespace llvm;
-using endianness = llvm::support::endianness;
 
 BinaryStreamReader::BinaryStreamReader(BinaryStreamRef Ref) : Stream(Ref) {}