ART: Fix things for valgrind

Wire up valgrind gtests. Add valgrind-test-art-host, currently
only depending on valgrind-test-art-host-gtest32.

Fix an Alloc setting to allow running valgrind.

Refactor the fault handler to manage (and correctly release) the
handlers.

Fix minor failure-case leaks exposed by tests.

Failing tests:

The optimizing compiler is leaking non-arena-ed structures
(e.g., assembler buffers), as code generators are not destroyed.
The solution has been moved to a follow-up CL.

Note: All 64b tests are failing as we cannot allocate a heap.

Change-Id: I7f854cfd098d9f68107ce492363e7dba9a82b9fa
diff --git a/compiler/utils/assembler.cc b/compiler/utils/assembler.cc
index 68b784a..e3045e1 100644
--- a/compiler/utils/assembler.cc
+++ b/compiler/utils/assembler.cc
@@ -92,6 +92,7 @@
 
   // Compute the relocation delta and switch to the new contents area.
   ptrdiff_t delta = new_contents - contents_;
+  delete[] contents_;
   contents_ = new_contents;
 
   // Update the cursor and recompute the limit.