[ELF] - Better diagnostic for relative relocation to an absolute value error.

Patch adds a filename to that error message.

I faced next error when debugged one of FreeBSD port:
error: relocation R_X86_64_PLT32 cannot refer to absolute symbol __tls_get_addr

error message was poor and this patch improves it to show the locations 
of symbol declaration and using.

Differential revision: https://reviews.llvm.org/D26508

llvm-svn: 286940
diff --git a/lld/ELF/LinkerScript.cpp b/lld/ELF/LinkerScript.cpp
index c8ca74a..a202dc5 100644
--- a/lld/ELF/LinkerScript.cpp
+++ b/lld/ELF/LinkerScript.cpp
@@ -65,7 +65,7 @@
 template <class ELFT> static void addRegular(SymbolAssignment *Cmd) {
   uint8_t Visibility = Cmd->Hidden ? STV_HIDDEN : STV_DEFAULT;
   Symbol *Sym = Symtab<ELFT>::X->addRegular(Cmd->Name, Visibility, STT_NOTYPE,
-                                            0, 0, STB_GLOBAL, nullptr);
+                                            0, 0, STB_GLOBAL, nullptr, nullptr);
   Cmd->Sym = Sym->body();
 
   // If we have no SECTIONS then we don't have '.' and don't call