Split RelativePatcher::ReserveSpace() into two.

Instead of passing nullptr and MethodReference(nullptr, 0u)
to ReserveSpace() at the end, call a newly created function
ReserveSpaceEnd().

Change-Id: I38815fe9464b4e1a919878b6e8577614f1058d00
diff --git a/compiler/linker/relative_patcher.cc b/compiler/linker/relative_patcher.cc
index 71f38b4..8ee87aa 100644
--- a/compiler/linker/relative_patcher.cc
+++ b/compiler/linker/relative_patcher.cc
@@ -38,6 +38,10 @@
       return offset;  // No space reserved; no patches expected.
     }
 
+    uint32_t ReserveSpaceEnd(uint32_t offset) OVERRIDE {
+      return offset;  // No space reserved; no patches expected.
+    }
+
     uint32_t WriteThunks(OutputStream* out ATTRIBUTE_UNUSED, uint32_t offset) OVERRIDE {
       return offset;  // No thunks added; no patches expected.
     }