build: Remove check_prereq.

check_prereq is a tool for recovery API v2, which has been obselete
since we moved to v3 in [1].

[1] commit e08991e02a7d678f2574e85289a34b2a9a537c82

Bug: 24621915
Change-Id: Ie96348fb56c5a3e029cac2417b59d8eb62dc085b
diff --git a/core/Makefile b/core/Makefile
index 237d5d1..8922f06 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1459,7 +1459,6 @@
 # We can't build static executables when SANITIZE_TARGET=address
 ifeq ($(strip $(SANITIZE_TARGET)),)
 built_ota_tools += \
-    $(call intermediates-dir-for,EXECUTABLES,check_prereq,,,$(TARGET_PREFER_32_BIT))/check_prereq \
     $(call intermediates-dir-for,EXECUTABLES,applypatch_static,,,$(TARGET_PREFER_32_BIT))/applypatch_static \
     $(call intermediates-dir-for,EXECUTABLES,updater,,,$(TARGET_PREFER_32_BIT))/updater
 endif
diff --git a/tools/check_prereq/Android.mk b/tools/check_prereq/Android.mk
deleted file mode 100644
index 4329aff..0000000
--- a/tools/check_prereq/Android.mk
+++ /dev/null
@@ -1,25 +0,0 @@
-# Copyright (C) 2009 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.
-
-LOCAL_PATH := $(call my-dir)
-include $(CLEAR_VARS)
-
-LOCAL_SRC_FILES := check_prereq.c
-LOCAL_MODULE := check_prereq
-LOCAL_FORCE_STATIC_EXECUTABLE := true
-LOCAL_MODULE_TAGS := eng
-LOCAL_C_INCLUDES +=
-LOCAL_STATIC_LIBRARIES += libcutils libc
-
-include $(BUILD_EXECUTABLE)
diff --git a/tools/check_prereq/check_prereq.c b/tools/check_prereq/check_prereq.c
deleted file mode 100644
index d7b8918..0000000
--- a/tools/check_prereq/check_prereq.c
+++ /dev/null
@@ -1,46 +0,0 @@
-/*
- * Copyright (C) 2009 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.
- */
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <sys/system_properties.h>
-#include <cutils/properties.h>
-
-// Compare the timestamp of the new build (passed on the command line)
-// against the current value of ro.build.date.utc.  Exit successfully
-// if the new build is newer than the current build (or if the
-// timestamps are the same).
-int main(int argc, char** argv) {
-  if (argc != 2) {
- usage:
-    fprintf(stderr, "usage: %s <timestamp>\n", argv[0]);
-    return 2;
-  }
-
-  char value[PROPERTY_VALUE_MAX];
-  char* default_value = "0";
-
-  property_get("ro.build.date.utc", value, default_value);
-
-  long current = strtol(value, NULL, 10);
-  char* end;
-  long install = strtol(argv[1], &end, 10);
-
-  printf("current build time: [%ld]  new build time: [%ld]\n",
-         current, install);
-
-  return (*end == 0 && current > 0 && install >= current) ? 0 : 1;
-}