clean up FORTIFY_SOURCE handling.

Avoid duplicating huge chunks of code.

Change-Id: Id6145cdfce781c5ffba2abaaa79681d25a7ab28f
diff --git a/libc/bionic/__strncat_chk.cpp b/libc/bionic/__strncat_chk.cpp
index 2ba8550..32a3962 100644
--- a/libc/bionic/__strncat_chk.cpp
+++ b/libc/bionic/__strncat_chk.cpp
@@ -55,17 +55,13 @@
     size_t sum;
     // sum = src_len + dest_len + 1 (with overflow protection)
     if (!safe_add3(&sum, src_len, dest_len, 1U)) {
-        __libc_android_log_print(ANDROID_LOG_FATAL, "libc",
-            "*** strncat integer overflow detected ***\n");
-        __libc_android_log_event_uid(BIONIC_EVENT_STRNCAT_INTEGER_OVERFLOW);
-        abort();
+        __fortify_chk_fail("strncat integer overflow",
+                             BIONIC_EVENT_STRNCAT_INTEGER_OVERFLOW);
     }
 
     if (sum > dest_buf_size) {
-        __libc_android_log_print(ANDROID_LOG_FATAL, "libc",
-            "*** strncat buffer overflow detected ***\n");
-        __libc_android_log_event_uid(BIONIC_EVENT_STRNCAT_BUFFER_OVERFLOW);
-        abort();
+        __fortify_chk_fail("strncat buffer overflow",
+                             BIONIC_EVENT_STRNCAT_BUFFER_OVERFLOW);
     }
 
     return strncat(dest, src, len);