Revert "Remove DCHECK that does not work for gtests."

And fix the code alignment in gtests.

This reverts commit 7d32dbc02beac2cb0217d52b61f2b3ef9974ffa6.

Change-Id: I68813c36d1493f2746ceb129b30a649350d6bc13
diff --git a/runtime/oat_quick_method_header.h b/runtime/oat_quick_method_header.h
index c9a2cfb..03cad08 100644
--- a/runtime/oat_quick_method_header.h
+++ b/runtime/oat_quick_method_header.h
@@ -43,6 +43,8 @@
   static OatQuickMethodHeader* FromCodePointer(const void* code_ptr) {
     uintptr_t code = reinterpret_cast<uintptr_t>(code_ptr);
     uintptr_t header = code - OFFSETOF_MEMBER(OatQuickMethodHeader, code_);
+    DCHECK(IsAlignedParam(code, GetInstructionSetAlignment(kRuntimeISA)) ||
+           IsAlignedParam(header, GetInstructionSetAlignment(kRuntimeISA)));
     return reinterpret_cast<OatQuickMethodHeader*>(header);
   }