Revert "Revert "Make sem_wait able to return errno EINTR for sdk > 23.""

This reverts commit 6d5108520225fd2c4b10ca63565545ec120aab4a.
And add missing bionic_sdk_version.h.

Change-Id: I24cc738b1fd1d26234c52afbc787f5b3c4a9c9cb
diff --git a/libc/bionic/libc_init_dynamic.cpp b/libc/bionic/libc_init_dynamic.cpp
index c34daef..ab48fb8 100644
--- a/libc/bionic/libc_init_dynamic.cpp
+++ b/libc/bionic/libc_init_dynamic.cpp
@@ -108,3 +108,9 @@
 
   exit(slingshot(args.argc, args.argv, args.envp));
 }
+
+extern "C" uint32_t android_get_application_target_sdk_version();
+
+uint32_t bionic_get_application_target_sdk_version() {
+  return android_get_application_target_sdk_version();
+}
diff --git a/libc/bionic/libc_init_static.cpp b/libc/bionic/libc_init_static.cpp
index 3cda1a2..d1494d7 100644
--- a/libc/bionic/libc_init_static.cpp
+++ b/libc/bionic/libc_init_static.cpp
@@ -26,6 +26,7 @@
  * SUCH DAMAGE.
  */
 
+#include <android/api-level.h>
 #include <elf.h>
 #include <errno.h>
 #include <stddef.h>
@@ -106,3 +107,7 @@
 
   exit(slingshot(args.argc, args.argv, args.envp));
 }
+
+uint32_t bionic_get_application_target_sdk_version() {
+  return __ANDROID_API__;
+}
diff --git a/libc/bionic/semaphore.cpp b/libc/bionic/semaphore.cpp
index b30c0b0..1981647 100644
--- a/libc/bionic/semaphore.cpp
+++ b/libc/bionic/semaphore.cpp
@@ -41,6 +41,7 @@
 
 #include "private/bionic_constants.h"
 #include "private/bionic_futex.h"
+#include "private/bionic_sdk_version.h"
 #include "private/bionic_time_conversions.h"
 
 // In this implementation, a semaphore contains a
@@ -220,7 +221,13 @@
       return 0;
     }
 
-    __futex_wait_ex(sem_count_ptr, shared, shared | SEMCOUNT_MINUS_ONE, false, nullptr);
+    int result = __futex_wait_ex(sem_count_ptr, shared, shared | SEMCOUNT_MINUS_ONE, false, nullptr);
+    if (bionic_get_application_target_sdk_version() > 23) {
+      if (result ==-EINTR) {
+        errno = EINTR;
+        return -1;
+      }
+    }
   }
 }
 
diff --git a/libc/private/bionic_sdk_version.h b/libc/private/bionic_sdk_version.h
new file mode 100644
index 0000000..871d25c
--- /dev/null
+++ b/libc/private/bionic_sdk_version.h
@@ -0,0 +1,24 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef _BIONIC_SDK_VERSION_H_
+#define _BIONIC_SDK_VERSION_H_
+
+#include <stdint.h>
+
+uint32_t bionic_get_application_target_sdk_version();
+
+#endif  // _BIONIC_SDK_VERSION_H_