ELF2: Use character literals for ELF file magic.

This is consitent with Support/ELF.h and more obvious than before.

llvm-svn: 251155
diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index 37c3705..cc3e630 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -705,9 +705,9 @@
   uint8_t *Buf = Buffer->getBufferStart();
   auto *EHdr = reinterpret_cast<Elf_Ehdr *>(Buf);
   EHdr->e_ident[EI_MAG0] = 0x7F;
-  EHdr->e_ident[EI_MAG1] = 0x45;
-  EHdr->e_ident[EI_MAG2] = 0x4C;
-  EHdr->e_ident[EI_MAG3] = 0x46;
+  EHdr->e_ident[EI_MAG1] = 'E';
+  EHdr->e_ident[EI_MAG2] = 'L';
+  EHdr->e_ident[EI_MAG3] = 'F';
   EHdr->e_ident[EI_CLASS] = ELFT::Is64Bits ? ELFCLASS64 : ELFCLASS32;
   EHdr->e_ident[EI_DATA] = ELFT::TargetEndianness == llvm::support::little
                                ? ELFDATA2LSB