Change assets to use 64-bit API

The asset system and supporting libraries were using off_t instead of
off64_t to access files larger than 2GB (32-bit signed). This change
replaces all off_t with off64_t and lseek64.

There is a new utils/Compat.h added for Mac OS compatibility.

Also fixed some size-related compiler warnings.

Bug: 3205336
Change-Id: I9097b3cb7a602e811fe52f245939d8975da55e9e
diff --git a/libs/utils/FileMap.cpp b/libs/utils/FileMap.cpp
index f1f8bda..c220a90 100644
--- a/libs/utils/FileMap.cpp
+++ b/libs/utils/FileMap.cpp
@@ -88,11 +88,12 @@
  *
  * Returns "false" on failure.
  */
-bool FileMap::create(const char* origFileName, int fd, off_t offset, size_t length, bool readOnly)
+bool FileMap::create(const char* origFileName, int fd, off64_t offset, size_t length,
+        bool readOnly)
 {
 #ifdef HAVE_WIN32_FILEMAP
     int     adjust;
-    off_t   adjOffset;
+    off64_t adjOffset;
     size_t  adjLength;
 
     if (mPageSize == -1) {
@@ -131,7 +132,7 @@
 #endif
 #ifdef HAVE_POSIX_FILEMAP
     int     prot, flags, adjust;
-    off_t   adjOffset;
+    off64_t adjOffset;
     size_t  adjLength;
 
     void* ptr;