Disable armeabi builds for Android and re-enable CI builds. (#4970)

armeabi support was removed from the Android NDK so we should no
longer build it.  Since this fixes the Android build failures this
commit also re-enables Travis Android builds.

While re-enabling Android builds, some recent changes broke C++98
support so this fixes those issues as well which include:
- Conditionally compiling use of move constructors, operators and
  std::move.
- Changing sample to use flatbuffers::unique_ptr rather than
  std::unique_ptr.

Finally, added the special "default_ptr_type" value for the
"cpp_ptr_type" attribute.  This expands to the value passed to
the "--cpp-ptr-type" argument of flatc.

1 files changed, 3 insertions, 1 deletions

diff --git a/docs/source/CppUsage.md b/docs/source/CppUsage.md
index fff04a9d..e13e1bad 100644
--- a/docs/source/CppUsage.md
+++ b/docs/source/CppUsage.md
@@ -240,7 +240,9 @@ influence this either globally (using the `--cpp-ptr-type` argument to
 `flatc`) or per field (using the `cpp_ptr_type` attribute) to by any smart
 pointer type (`my_ptr<T>`), or by specifying `naked` as the type to get `T *`
 pointers. Unlike the smart pointers, naked pointers do not manage memory for
-you, so you'll have to manage their lifecycles manually.
+you, so you'll have to manage their lifecycles manually.  To reference the
+pointer type specified by the `--cpp-ptr-type` argument to `flatc` from a
+flatbuffer field set the `cpp_ptr_type` attribute to `default_ptr_type`.
 
 
 # Using different string type.