Revert "Revert "Add implicit null and stack checks for x86""

Fixes x86_64 cross compile issue.  Removes command line options
and property to set implicit checks - this is hard coded now.

This reverts commit 3d14eb620716e92c21c4d2c2d11a95be53319791.

Change-Id: I5404473b5aaf1a9c68b7181f5952cb174d93a90d
diff --git a/sigchainlib/Android.mk b/sigchainlib/Android.mk
index 8e25339..20c8cac 100644
--- a/sigchainlib/Android.mk
+++ b/sigchainlib/Android.mk
@@ -28,3 +28,16 @@
 LOCAL_ADDITIONAL_DEPENDENCIES := $(LOCAL_PATH)/Android.mk
 LOCAL_ADDITIONAL_DEPENDENCIES += art/build/Android.common_build.mk
 include $(BUILD_SHARED_LIBRARY)
+
+# Build host library.
+include $(CLEAR_VARS)
+LOCAL_CPP_EXTENSION := $(ART_CPP_EXTENSION)
+LOCAL_MODULE_TAGS := optional
+LOCAL_IS_HOST_MODULE := true
+LOCAL_CFLAGS += $(ART_HOST_CFLAGS)
+LOCAL_SRC_FILES := sigchain.cc
+LOCAL_MODULE:= libsigchain
+LOCAL_ADDITIONAL_DEPENDENCIES += $(LOCAL_PATH)/Android.mk
+LOCAL_LDLIBS = -ldl
+LOCAL_MULTILIB := both
+include $(BUILD_HOST_SHARED_LIBRARY)
diff --git a/sigchainlib/sigchain.cc b/sigchainlib/sigchain.cc
index 5a5805f..458ad69 100644
--- a/sigchainlib/sigchain.cc
+++ b/sigchainlib/sigchain.cc
@@ -14,7 +14,13 @@
  * limitations under the License.
  */
 
+#ifdef HAVE_ANDROID_OS
 #include <android/log.h>
+#else
+#include <stdarg.h>
+#include <iostream>
+#endif
+
 #include <dlfcn.h>
 #include <signal.h>
 #include <stdio.h>
@@ -67,7 +73,11 @@
   va_list ap;
   va_start(ap, format);
   vsnprintf(buf, sizeof(buf), format, ap);
+#ifdef HAVE_ANDROID_OS
   __android_log_write(ANDROID_LOG_ERROR, "libsigchain", buf);
+#else
+  std::cout << buf << "\n";
+#endif
   va_end(ap);
 }
 
@@ -104,10 +114,16 @@
   if ((action.sa_flags & SA_SIGINFO) == 0) {
     if (action.sa_handler != NULL) {
       action.sa_handler(sig);
+    } else {
+       signal(sig, SIG_DFL);
+       raise(sig);
     }
   } else {
     if (action.sa_sigaction != NULL) {
       action.sa_sigaction(sig, info, context);
+    } else {
+       signal(sig, SIG_DFL);
+       raise(sig);
     }
   }
 }