Bionic malloc debug: add a new option "abort_on_error"

This new option causes an abort after malloc debug detects an error.
This allows vendors to get process coredumps to analyze memory for
corruption.

Bug: 123009873
Test: New test cases added for unit tests and config tests.

Change-Id: I6b480af7f747d6a82f61e8bf3df204a5f7ba017f
diff --git a/libc/malloc_debug/GuardData.cpp b/libc/malloc_debug/GuardData.cpp
index debc14e..c307dc9 100644
--- a/libc/malloc_debug/GuardData.cpp
+++ b/libc/malloc_debug/GuardData.cpp
@@ -64,6 +64,9 @@
   error_log("Backtrace at time of failure:");
   BacktraceAndLog();
   error_log(LOG_DIVIDER);
+  if (g_debug->config().options() & ABORT_ON_ERROR) {
+    abort();
+  }
 }
 
 FrontGuardData::FrontGuardData(DebugData* debug_data, const Config& config, size_t* offset)