lld: set sh_link and sh_info for .rela.plt sections

ELF spec says that for SHT_REL and SHT_RELA sh_link should reference the
associated string table and sh_info should reference the "section to
which the relocation applies."  ELF Tool Chain's elfcopy / strip use
this (in part) to control whether or not the relocation entry is copied
to the output.

Obtained from:	llvm review D52830

contrib/llvm/tools/lld/ELF/SyntheticSections.cpp

@@ -1372,11 +1372,15 @@ void RelocationBaseSection::addReloc(const DynamicReloc &Reloc) {
 void RelocationBaseSection::finalizeContents() {
   // If all relocations are R_*_RELATIVE they don't refer to any
   // dynamic symbol and we don't need a dynamic symbol table. If that
-  // is the case, just use 0 as the link.
-  Link = InX::DynSymTab ? InX::DynSymTab->getParent()->SectionIndex : 0;
-
-  // Set required output section properties.
-  getParent()->Link = Link;
+  // is the case, just use the index of the regular symbol table section.
+  getParent()->Link = InX::DynSymTab ?
+    InX::DynSymTab->getParent()->SectionIndex :
+    InX::SymTab->getParent()->SectionIndex;
+
+  if (InX::RelaIplt == this)
+    getParent()->Info = InX::Iplt->getParent()->SectionIndex;
+  else if (InX::RelaPlt == this)
+    getParent()->Info = InX::Plt->getParent()->SectionIndex;
 }
 
 template <class ELFT>

lib/clang/include/lld/Common/Version.inc

@@ -7,4 +7,4 @@
 
 #define LLD_REPOSITORY_STRING "FreeBSD"
 // <Upstream revision at import>-<Local identifier in __FreeBSD_version style>
-#define LLD_REVISION_STRING "335540-1200004"
+#define LLD_REVISION_STRING "335540-1200005"