COMPMID-1626: Fixed VGG 16/19 bad_alloc failure.

Some systems don't have enough memory to run the VGG networks, for example
on systems with only 2GB memory the VGG example fails throwing a bad_alloc exception.

This patch introduces the concept of global memory policy in ACL, the policy
is a mechanism which could be used by the library's functions to try to reduce
memory consumption on systems with limited memory.

In this specific case the VGG examples set the policy to MINIMIZE. The GEMM
function checks if the policy is MINIMIZE and in this case does not use the
pretransposed weights path as this requires considerable more memory.

Change-Id: I53abc3c9c64d045d8306793ffc9d24b28e228b7b
diff --git a/examples/graph_vgg19.cpp b/examples/graph_vgg19.cpp
index ff7cf75..3b17735 100644
--- a/examples/graph_vgg19.cpp
+++ b/examples/graph_vgg19.cpp
@@ -40,6 +40,16 @@
     }
     bool do_setup(int argc, char **argv) override
     {
+        // Check if the system has enough RAM to run the example, systems with less than 2GB have
+        // to hint the API to minimize memory consumption otherwise it'll run out of memory and
+        // fail throwing the bad_alloc exception
+        arm_compute::MEMInfo meminfo;
+        const size_t         mem_total = meminfo.get_total_in_kb();
+        if(mem_total <= arm_compute::MEMInfo::TWO_GB_IN_KB)
+        {
+            arm_compute::MEMInfo::set_policy(arm_compute::MemoryPolicy::MINIMIZE);
+        }
+
         // Parse arguments
         cmd_parser.parse(argc, argv);