[ORC-RT][llvm-jitlink] Fix a buggy check in ORC-RT MachO TLV deregistration.

The check was failing because it was matching against the end of the range, not
the start.

This bug wasn't causing the ORC-RT MachO TLV regression test to fail because
we were only logging deallocation errors (including TLV deregistration errors)
and not actually returning a failure code. This commit updates llvm-jitlink to
report the errors properly.

Author: lhames

compiler-rt/lib/orc/macho_platform.cpp

@@ -308,7 +308,7 @@ Error MachOPlatformRuntimeState::registerThreadDataSection(
 Error MachOPlatformRuntimeState::deregisterThreadDataSection(
     span<const char> ThreadDataSection) {
   std::lock_guard<std::mutex> Lock(ThreadDataSectionsMutex);
-  auto I = ThreadDataSections.find(ThreadDataSection.end());
+  auto I = ThreadDataSections.find(ThreadDataSection.data());
   if (I == ThreadDataSections.end())
     return make_error<StringError>("Attempt to deregister unknown thread data "
                                    "section");

llvm/tools/llvm-jitlink/llvm-jitlink.cpp

@@ -1643,6 +1643,7 @@ int main(int argc, char *argv[]) {
   }
 
   // Destroy the session.
+  ExitOnErr(S->ES.endSession());
   S.reset();
 
   // If the executing code set a test result override then use that.