ART: More header cleanup - mem_map.h

Move MemMap maps_ into cc file and move allocator include. Remove
other unused includes. Force clients to import sys/mman.h if they
need it. Try to lower dependencies on ART by using libbase helpers
more.

Test: mmma art
Change-Id: I8f31e5f371789b3d72e12af377181fee2ac9a611
diff --git a/runtime/dex_file.cc b/runtime/dex_file.cc
index 688f95b..625794e 100644
--- a/runtime/dex_file.cc
+++ b/runtime/dex_file.cc
@@ -22,6 +22,7 @@
 #include <stdlib.h>
 #include <string.h>
 #include <sys/file.h>
+#include <sys/mman.h>  // For the PROT_* and MAP_* constants.
 #include <sys/stat.h>
 #include <zlib.h>