[BOLT] Fix the initialization of DWARFDataExtractor

Without this patch, we pass Endian as one of the parameters to the
constructor of DWARFDataExtractor.  The problem is that Endian is of:

  enum endianness {big, little, native};

whereas the constructor is expecting "bool IsLittleEndian".  That is,
we are relying on an implicit conversion to convert big and little to
false and true, respectively.

When we migrate llvm::support::endianness to std::endian in future, we
can no longer rely on an implicit conversion because std::endian is
declared with "enum class".  Even if we could, the conversion would
not be guaranteed to work because, for example, libcxx defines:

  enum class endian {
    little = 0xDEAD,
    big = 0xFACE,
    :

where big and little are not boolean values.

This patch fixes the problem by properly converting Endian to a
boolean value.

Author: kazutakahirata

bolt/lib/Core/DebugData.cpp

@@ -495,7 +495,8 @@ void DebugAddrWriterDwarf5::update(DIEBuilder &DIEBlder, DWARFUnit &CU) {
   const endianness Endian =
       BC->DwCtx->isLittleEndian() ? support::little : support::big;
   const DWARFSection &AddrSec = BC->DwCtx->getDWARFObj().getAddrSection();
-  DWARFDataExtractor AddrData(BC->DwCtx->getDWARFObj(), AddrSec, Endian, 0);
+  DWARFDataExtractor AddrData(BC->DwCtx->getDWARFObj(), AddrSec,
+                              Endian == support::little, 0);
   DWARFDebugAddrTable AddrTable;
   DIDumpOptions DumpOpts;
   constexpr uint32_t HeaderSize = 8;