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/erts/emulator/sys/unix/sys.c b/erts/emulator/sys/unix/sys.c
index 865cb50a56..c3d7440409 100644
--- a/erts/emulator/sys/unix/sys.c
+++ b/erts/emulator/sys/unix/sys.c
@@ -149,6 +149,13 @@ extern void erl_crash_dump(char* file, int line, char* fmt, ...);
 
 #define DIR_SEPARATOR_CHAR    '/'
 
+#if defined(__ANDROID__)
+#define SHELL "/system/bin/sh"
+#else
+#define SHELL "/bin/sh"
+#endif /* __ANDROID__ */
+
+
 #if defined(DEBUG)
 #define ERL_BUILD_TYPE_MARKER ".debug"
 #elif defined(PURIFY)
@@ -1596,7 +1603,7 @@ static ErlDrvData spawn_start(ErlDrvPort port_num, char* name, SysDriverOpts* op
 		    }
 		}
 	    } else {
-		execle("/bin/sh", "sh", "-c", cmd_line, (char *) NULL, new_environ);
+		execle(SHELL, "sh", "-c", cmd_line, (char *) NULL, new_environ);
 	    }
 	child_error:
 	    _exit(1);
@@ -1717,7 +1724,7 @@ static ErlDrvData spawn_start(ErlDrvPort port_num, char* name, SysDriverOpts* op
 	fcntl(i, F_SETFD, 1);
 
     qnx_spawn_options.flags = _SPAWN_SETSID;
-    if ((pid = spawnl(P_NOWAIT, "/bin/sh", "/bin/sh", "-c", cmd_line, 
+    if ((pid = spawnl(P_NOWAIT, SHELL, SHELL, "-c", cmd_line, 
                       (char *) 0)) < 0) {
 	erts_free(ERTS_ALC_T_TMP, (void *) cmd_line);
         reset_qnx_spawn();