Fixes a build issue with libc++ configured with _LIBCPP_RAW_ITERATORS (ADL not effective)
```
llvm/lib/CodeGen/TargetLoweringObjectFileImpl.cpp:1602:3: error: no matching function for call to 'transform'
transform(HexString.begin(), HexString.end(), HexString.begin(), tolower);
^~~~~~~~~
```
Reviewed By: MaskRay
Differential Revision: https://reviews.llvm.org/D80475
static std::string APIntToHexString(const APInt &AI) {
unsigned Width = (AI.getBitWidth() / 8) * 2;
std::string HexString = AI.toString(16, /*Signed=*/false);
- transform(HexString.begin(), HexString.end(), HexString.begin(), tolower);
+ llvm::transform(HexString, HexString.begin(), tolower);
unsigned Size = HexString.size();
assert(Width >= Size && "hex string is too large!");
HexString.insert(HexString.begin(), Width - Size, '0');