[AMDGPU][HIP] Change default DWARF version to 4

Summary:
Tooling around DWARF 5 is still not mature enough for this to be a sane
default, and the AMDGPU and HIP toolchains should agree on a single
default.

Subscribers: kzhuravl, jvesely, wdng, nhaehnle, yaxunl, aprantl, dstuttard, tpr, t-tye, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D70191
diff --git a/clang/lib/Driver/ToolChains/AMDGPU.h b/clang/lib/Driver/ToolChains/AMDGPU.h
index 5585cc5..f4c78be 100644
--- a/clang/lib/Driver/ToolChains/AMDGPU.h
+++ b/clang/lib/Driver/ToolChains/AMDGPU.h
@@ -55,7 +55,7 @@
 public:
   AMDGPUToolChain(const Driver &D, const llvm::Triple &Triple,
                   const llvm::opt::ArgList &Args);
-  unsigned GetDefaultDwarfVersion() const override { return 5; }
+  unsigned GetDefaultDwarfVersion() const override { return 4; }
   bool IsIntegratedAssemblerDefault() const override { return true; }
   bool IsMathErrnoDefault() const override { return false; }