Raspberry PI / Android a minimal cross-compile configuration

Enable a cross compile Erlang/OTP platform to Android or Raspberry PI
using Android NDK. Port emulator and core application to support target
HW platform. Exclude any add-on services required for OTP platform deployment
into target hardware due to device fragmentation and jail-break requirements.

 * fix erts/emulator/beam/sys.h
   Disable redefinition of __noreturn macro

 * port erts/emulator/sys/unix/erl_child_setup.c
   Use techniques proposed by https://code.google.com/p/erlang4android to
   access system properties

 * fix erts/emulator/sys/unix/erl_unix_sys_ddll.c
   The static linking of emulator cannot find dlerror(), dlopen() symbols

 * port erts/emulator/sys/unix/sys.c
   make path to shell configurable at build time

 * port erts/etc/common/Makefile.in
   disable librt for *-linux-androideabi

 * port erts/lib_src/pthread/ethread.c
   Use techniques proposed by https://code.google.com/p/erlang4android to
   disable emulator crash if kernel threads are on. Replace unreliable
   pthread_sigmask() by sigprocmask()

 * port lib/erl_interface/src/connect/ei_connect.c
   Disable call to undefined gethostid()

 * port lib/erl_interface/src/connect/ei_resolve.c
   Use gethostbyname_r() on Android platform

1 files changed, 9 insertions, 2 deletions

diff --git a/lib/kernel/src/os.erl b/lib/kernel/src/os.erl
index 9ffa9adeab..3bda391b8e 100644
--- a/lib/kernel/src/os.erl
+++ b/lib/kernel/src/os.erl
@@ -230,7 +230,9 @@ unix_cmd(Cmd) ->
 %% and the commands are read from standard input. We set the
 %% $1 parameter for easy identification of the resident shell.
 %%
--define(SHELL, "/bin/sh -s unix:cmd 2>&1").
+-define(ROOT,          "/").
+-define(ROOT_ANDROID,  "/system").
+-define(SHELL, "bin/sh -s unix:cmd 2>&1").
 -define(PORT_CREATOR_NAME, os_cmd_port_creator).
 
 %%
@@ -280,7 +282,12 @@ start_port_srv(Request) ->
     end.
 
 start_port_srv_handle({Ref,Client}) ->
-    Reply = try open_port({spawn, ?SHELL},[stream]) of
+    Path  = case lists:reverse(erlang:system_info(system_architecture)) of
+      % androideabi
+      "ibaediordna" ++ _ -> filename:join([?ROOT_ANDROID, ?SHELL]);
+      _ -> filename:join([?ROOT, ?SHELL])
+    end,
+    Reply = try open_port({spawn, Path},[stream]) of
 		Port when is_port(Port) ->
 		    (catch port_connect(Port, Client)),
 		    unlink(Port),