Add config option to use dlmalloc instead of mheap

Configure w/ --enable-dlmalloc, see .../build-data/platforms/vpp.mk

src/vppinfra/dlmalloc.[ch] are slightly modified versions of the
well-known Doug Lea malloc. Main advantage: dlmalloc mspaces have no
inherent size limit.

Change-Id: I19b3f43f3c65bcfb82c1a265a97922d01912446e
Signed-off-by: Dave Barach <dave@barachs.net>
diff --git a/src/vcl/vcl_cfg.c b/src/vcl/vcl_cfg.c
index 338a6fa..f25c8fc 100644
--- a/src/vcl/vcl_cfg.c
+++ b/src/vcl/vcl_cfg.c
@@ -200,7 +200,7 @@
       ASSERT (vcl_mem != MAP_FAILED);
       return;
     }
-  heap = clib_mem_init (vcl_mem, vcl_cfg->heapsize);
+  heap = clib_mem_init_thread_safe (vcl_mem, vcl_cfg->heapsize);
   if (!heap)
     {
       clib_warning ("VCL<%d>: ERROR: clib_mem_init() failed!", getpid ());