Move sysMapFile and sysReleaseMap into MemMapping class.

Test: recovery_component_test
Test: recovery_unit_test
Test: Apply an OTA on angler.
Change-Id: I7170f03e4ce1fe06184ca1d7bcce0a695f33ac4d
diff --git a/updater/updater.cpp b/updater/updater.cpp
index c09e267..749c86a 100644
--- a/updater/updater.cpp
+++ b/updater/updater.cpp
@@ -89,7 +89,7 @@
 
   const char* package_filename = argv[3];
   MemMapping map;
-  if (sysMapFile(package_filename, &map) != 0) {
+  if (!map.MapFile(package_filename)) {
     LOG(ERROR) << "failed to map package " << argv[3];
     return 3;
   }
@@ -213,7 +213,6 @@
   if (updater_info.package_zip) {
     CloseArchive(updater_info.package_zip);
   }
-  sysReleaseMap(&map);
 
   return 0;
 }