[LLVM-3.9] Increase PIELevel

Previously, we had a PositionIndependentExecutable, now we simply
choose the highest level. This should be equivalent.

:cake:

Author: badboy

src/rustllvm/PassWrapper.cpp

@@ -418,6 +418,6 @@ LLVMRustGetModuleDataLayout(LLVMModuleRef M) {
 extern "C" void
 LLVMRustSetModulePIELevel(LLVMModuleRef M) {
 #if LLVM_VERSION_MINOR >= 9
-    unwrap(M)->setPIELevel(PIELevel::Level::Default);
+    unwrap(M)->setPIELevel(PIELevel::Level::Large);
 #endif
 }