ARM/ARM64: Clean up relative patchers.

Test: Rely on TreeHugger.
Bug: 29516974
Bug: 30126666
Bug: 36141117
Change-Id: I5c452bfae79e63de09211f396abc5413ac7a3e4d
diff --git a/compiler/linker/arm/relative_patcher_thumb2.h b/compiler/linker/arm/relative_patcher_thumb2.h
index 7e787d2..183e5e6 100644
--- a/compiler/linker/arm/relative_patcher_thumb2.h
+++ b/compiler/linker/arm/relative_patcher_thumb2.h
@@ -94,13 +94,13 @@
     kField,   // Field get or array get with constant offset (i.e. constant index).
     kArray,   // Array get with index in register.
     kGcRoot,  // GC root load.
-    kLast
+    kLast = kGcRoot
   };
 
   enum class BakerReadBarrierWidth : uint8_t {
     kWide,          // 32-bit LDR (and 32-bit NEG if heap poisoning is enabled).
     kNarrow,        // 16-bit LDR (and 16-bit NEG if heap poisoning is enabled).
-    kLast
+    kLast = kNarrow
   };
 
   static constexpr size_t kBitsForBakerReadBarrierKind =