[clang] update of the DragonFlyBSD's driver for the 5.8.x releases.

[sepavloff]

LGTM.

clang/lib/Driver/ToolChains/DragonFly.cpp

void dragonfly::Linker::ConstructJob(Compilation &C, const JobAction &JA,
   }
 
   Args.AddAllArgs(CmdArgs,
                   {options::OPT_L, options::OPT_T_Group, options::OPT_e});
 
   AddLinkerInputs(getToolChain(), Inputs, Args, CmdArgs, JA);
 
   if (!Args.hasArg(options::OPT_nostdlib, options::OPT_nodefaultlibs)) {
-    CmdArgs.push_back("-L/usr/lib/gcc50");
+    CmdArgs.push_back("-L/usr/lib/gcc80");
 
     if (!Args.hasArg(options::OPT_static)) {
       CmdArgs.push_back("-rpath");
-      CmdArgs.push_back("/usr/lib/gcc50");
+      CmdArgs.push_back("/usr/lib/gcc80");
     }
 
     if (D.CCCIsCXX()) {
       if (getToolChain().ShouldLinkCXXStdlib(Args))
         getToolChain().AddCXXStdlibLibArgs(Args, CmdArgs);
       CmdArgs.push_back("-lm");
     }
 
DragonFly::DragonFly(const Driver &D, const llvm::Triple &Triple,
 
   // Path mangling to find libexec
   getProgramPaths().push_back(getDriver().getInstalledDir());
   if (getDriver().getInstalledDir() != getDriver().Dir)
     getProgramPaths().push_back(getDriver().Dir);
 
   getFilePaths().push_back(getDriver().Dir + "/../lib");
   getFilePaths().push_back("/usr/lib");
-  getFilePaths().push_back("/usr/lib/gcc50");
+  getFilePaths().push_back("/usr/lib/gcc80");
 }
 
 Tool *DragonFly::buildAssembler() const {
   return new tools::dragonfly::Assembler(*this);
 }
 
 Tool *DragonFly::buildLinker() const {
   return new tools::dragonfly::Linker(*this);
 }