[Comgr] Removing target specification from HIP compilation

Reported here: #92

Instead of hardcoding the -target option, allow clang to use
the default target. This avoids issues when using musl, which
requires a 'x86_64-unknown-linux-musl' target.

Change-Id: I6a24dda4078f914e47bf3b4b2715dbce9d1a513f

amd/comgr/src/comgr-compiler.cpp

@@ -668,7 +668,8 @@ AMDGPUCompiler::executeInProcessDriver(ArrayRef<const char *> Args) {
   DiagnosticsEngine Diags(DiagID, &*DiagOpts, DiagClient);
   ProcessWarningOptions(Diags, *DiagOpts, /*ReportDiags=*/false);
 
-  Driver TheDriver((Twine(env::getLLVMPath()) + "/bin/clang").str(), "", Diags);
+  Driver TheDriver((Twine(env::getLLVMPath()) + "/bin/clang").str(),
+                   llvm::sys::getDefaultTargetTriple(), Diags);
   TheDriver.setTitle("AMDGPU Code Object Manager");
   TheDriver.setCheckInputsExist(false);
 
@@ -1052,8 +1053,6 @@ amd_comgr_status_t AMDGPUCompiler::addCompilationFlags() {
   case AMD_COMGR_LANGUAGE_HIP:
     Args.push_back("hip");
     Args.push_back("-std=c++11");
-    Args.push_back("-target");
-    Args.push_back("x86_64-unknown-linux-gnu");
     Args.push_back("--cuda-device-only");
     Args.push_back("-isystem");
     Args.push_back(ROCMIncludePath.c_str());