hammerhead: switch back to dlmalloc

Experiment for a while with hammerhead switched back to dlmalloc (from
jemalloc), on the theory that jemalloc was contributing to excessive
page-allocator fragmentation. We will revisit this after the holidays once we
have data from users.

b/18069309 N5 running L can't run as many apps simultaneously as running K

Change-Id: If69ddc33181e133045ffc1a6d98cdfc76078b388
Signed-off-by: Iliyan Malchev <malchev@google.com>
diff --git a/BoardConfig.mk b/BoardConfig.mk
index fd48f5e..4f1142b 100644
--- a/BoardConfig.mk
+++ b/BoardConfig.mk
@@ -155,5 +155,7 @@
 # Enable Minikin text layout engine (will be the default soon)
 USE_MINIKIN := true
 
+MALLOC_IMPL := dlmalloc
+
 # Include an expanded selection of fonts
 EXTENDED_FONT_FOOTPRINT := true