Kaleidoscope-Ch8: use Reloc::PIC_

which has better portability across different OSes.
In addition, on many ELF OSes, this output relocatable file can be
linked without -no-pie.

Author: MaskRay

llvm/docs/tutorial/MyFirstLanguageFrontend/LangImpl08.rst

@@ -105,17 +105,16 @@ To see which features and CPUs that LLVM knows about, we can use
       3dnowa                - Enable 3DNow! Athlon instructions.
       ...
 
-For our example, we'll use the generic CPU without any additional
-features, options or relocation model.
+For our example, we'll use the generic CPU without any additional feature or
+target option.
 
 .. code-block:: c++
 
   auto CPU = "generic";
   auto Features = "";
 
   TargetOptions opt;
-  auto RM = std::optional<Reloc::Model>();
-  auto TargetMachine = Target->createTargetMachine(TargetTriple, CPU, Features, opt, RM);
+  auto TargetMachine = Target->createTargetMachine(TargetTriple, CPU, Features, opt, Reloc::PIC_);
 
 
 Configuring the Module

llvm/examples/Kaleidoscope/Chapter8/toy.cpp

@@ -1242,9 +1242,8 @@ int main() {
   auto Features = "";
 
   TargetOptions opt;
-  auto RM = std::optional<Reloc::Model>();
-  auto TheTargetMachine =
-      Target->createTargetMachine(TargetTriple, CPU, Features, opt, RM);
+  auto TheTargetMachine = Target->createTargetMachine(
+      TargetTriple, CPU, Features, opt, Reloc::PIC_);
 
   TheModule->setDataLayout(TheTargetMachine->createDataLayout());