Mac build fixes.

This gets us pretty close. There are a few problems with libraries we depend
on (system/core/liblog and external/icu4c) that I have workarounds for, and
a problem with gtest that I haven't yet worked around that prevents us from
linking any of the tests. But this at least gives us a Mac dex2oat binary.

Change-Id: Iac39a6c2963c3d37ab2165d7d1a70e303ba22c45
diff --git a/src/mem_map.cc b/src/mem_map.cc
index 09391df..673098d 100644
--- a/src/mem_map.cc
+++ b/src/mem_map.cc
@@ -40,7 +40,10 @@
 }
 
 void CheckMapRequest(byte* addr, size_t length) {
-#ifndef NDEBUG
+#if !defined(NDEBUG)
+#if defined(__APPLE__)
+  UNIMPLEMENTED(WARNING);
+#else
   if (addr == NULL) {
     return;
   }
@@ -101,6 +104,7 @@
     CHECK(i != std::string::npos) << "Failed to find newline from pos " << i << "\n" << maps;
   }
 #endif
+#endif
 }
 
 MemMap* MemMap::MapAnonymous(const char* name, byte* addr, size_t length, int prot) {