[Driver] Define BareMetal::HasNativeLLVMSupport to return true

D33259 switched the default linker to ld.lld which supports LLVM LTO.
We can support LTO compile/link in one command and drop the
`unable to pass LLVM bit-code files to linker` error.

Fix #52807

Author: MaskRay

clang/lib/Driver/ToolChains/BareMetal.h

@@ -37,6 +37,7 @@ class LLVM_LIBRARY_VISIBILITY BareMetal : public ToolChain {
   bool useIntegratedAs() const override { return true; }
   bool isBareMetal() const override { return true; }
   bool isCrossCompiling() const override { return true; }
+  bool HasNativeLLVMSupport() const override { return true; }
   bool isPICDefault() const override { return false; }
   bool isPIEDefault(const llvm::opt::ArgList &Args) const override {
     return false;

clang/test/Driver/native-llvm.c

@@ -3,3 +3,5 @@
 
 // RUN: %clang -### -flto -target x86_64-unknown-unknown %s 2>&1 | FileCheck %s
 // CHECK: error: {{.*}} unable to pass LLVM bit-code files to linker
+
+// RUN: %clang -### -flto --target=arm-none-eabi %s 2>&1 | FileCheck /dev/null --implicit-check-not=error: