[llc][NFC] Remove unreachable return statement (#169915)

`reportError()` is a `[[noreturn]]` that calls `exit(1)`.

Author: tomershafir

llvm/tools/llc/llc.cpp

@@ -355,13 +355,11 @@ static std::unique_ptr<ToolOutputFile> GetOutputStream(Triple::OSType OS) {
   if (!Binary)
     OpenFlags |= sys::fs::OF_TextWithCRLF;
   auto FDOut = std::make_unique<ToolOutputFile>(OutputFilename, EC, OpenFlags);
-  if (EC) {
+  if (EC)
     reportError(EC.message());
-    return nullptr;
-  }
-
   return FDOut;
 }
+
 // main - Entry point for the llc compiler.
 //
 int main(int argc, char **argv) {