[asan] add flags: disable_core, abort_on_error and unmap_shadow_on_exit

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@154159 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/asan/asan_posix.cc b/lib/asan/asan_posix.cc
index 03bd057..cd198bc 100644
--- a/lib/asan/asan_posix.cc
+++ b/lib/asan/asan_posix.cc
@@ -140,6 +140,10 @@
   _exit(exitcode);
 }
 
+void Abort() {
+  abort();
+}
+
 int Atexit(void (*function)(void)) {
   return atexit(function);
 }