Clean up ImageHeader section getters.

Test: m art-test-host-gtest
Test: testrunner.py --host
Change-Id: Iaea7ce6f9bc3ff3c6d9bb6fb598aa62333ebf30c
diff --git a/patchoat/patchoat.cc b/patchoat/patchoat.cc
index efa2969..f54e81f 100644
--- a/patchoat/patchoat.cc
+++ b/patchoat/patchoat.cc
@@ -468,7 +468,7 @@
 };
 
 void PatchOat::PatchInternedStrings(const ImageHeader* image_header) {
-  const auto& section = image_header->GetImageSection(ImageHeader::kSectionInternedStrings);
+  const auto& section = image_header->GetInternedStringsSection();
   InternTable temp_table;
   // Note that we require that ReadFromMemory does not make an internal copy of the elements.
   // This also relies on visit roots not doing any verification which could fail after we update
@@ -479,7 +479,7 @@
 }
 
 void PatchOat::PatchClassTable(const ImageHeader* image_header) {
-  const auto& section = image_header->GetImageSection(ImageHeader::kSectionClassTable);
+  const auto& section = image_header->GetClassTableSection();
   if (section.Size() == 0) {
     return;
   }