[OpenMP] Remove `-Bsymbolic` flag for device linking in the GNU toolchain

[jhuber6]

Summary

Previously, OpenMP linking would be done explicitly in a linker stage.
For x86_64 offloading this would just use the host linker, which could
be the bfd linker. This linker had problems linking relocations
against variables with protected visibility so we force -Bsymbolic
when linking. After the deprecation of the old offloading driver this
code is no longer used and can be removed.

[tianshilei1992]

LG

clang/lib/Driver/ToolChains/Gnu.cpp

if (ToolChain.ShouldLinkCXXStdlib(Args)) {
         CmdArgs.push_back("-Bstatic");
       ToolChain.AddCXXStdlibLibArgs(Args, CmdArgs);
       if (OnlyLibstdcxxStatic)
         CmdArgs.push_back("-Bdynamic");
     }
     CmdArgs.push_back("-lm");
   }
 
-  // If we are linking for the device all symbols should be bound locally. The
-  // symbols are already protected which makes this redundant. This is only
-  // necessary to work around a problem in bfd.
-  // TODO: Remove this once 'lld' becomes the only linker for offloading.
-  if (JA.isDeviceOffloading(Action::OFK_OpenMP))
-    CmdArgs.push_back("-Bsymbolic");
-
   // Silence warnings when linking C code with a C++ '-stdlib' argument.
   Args.ClaimAllArgs(options::OPT_stdlib_EQ);
 
   // Additional linker set-up and flags for Fortran. This is required in order
   // to generate executables. As Fortran runtime depends on the C runtime,
   // these dependencies need to be listed before the C runtime below (i.e.
   // AddRuntTimeLibs).
   if (D.IsFlangMode()) {