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, 5 insertions, 1 deletions

diff --git a/erts/emulator/beam/sys.h b/erts/emulator/beam/sys.h
index e273056a2b..05f07e57b2 100644
--- a/erts/emulator/beam/sys.h
+++ b/erts/emulator/beam/sys.h
@@ -154,10 +154,14 @@ typedef ERTS_SYS_FD_TYPE ErtsSysFdType;
 /* In VC++, noreturn is a declspec that has to be before the types,
  * but in GNUC it is an att ribute to be placed between return type
  * and function name, hence __decl_noreturn <types> __noreturn <function name>
+ *
+ * at some platforms (e.g. Android) __noreturn is defined at sys/cdef.h
  */
 #if __GNUC__
 #  define __decl_noreturn
-#  define __noreturn __attribute__((noreturn))
+#  ifndef __noreturn
+#     define __noreturn __attribute__((noreturn))
+#  endif
 #else
 #  if defined(__WIN32__) && defined(_MSC_VER)
 #    define __noreturn