CLOUDSTACK-5993: Cloud agent fails to start on 32-bit system vms (cpvm and ssvm) created with 4GB RAM offering

Capped the max heap size of the JVM at 2600M for 32-bit system VMs. For 64-bit, existing logic works fine.
(cherry picked from commit 1ae02009b5)

Signed-off-by: Animesh Chaturvedi <animesh@apache.org>

systemvm/scripts/_run.sh

@@ -61,4 +61,11 @@ then
   maxmem=$eightypcnt
 fi
 
+if [ "$(uname -m | grep '64')" == "" ]; then
+  let "maxmem32bit=2600"
+  if [ $maxmem -gt $maxmem32bit ]; then
+    maxmem=$maxmem32bit
+  fi
+fi
+
 java -Djavax.net.ssl.trustStore=./certs/realhostip.keystore -Dlog.home=$LOGHOME -mx${maxmem}m -cp $CP com.cloud.agent.AgentShell $keyvalues $@