Revert "Update to Netty 4.0.37"

This reverts commit e8d7fe8a28.

build.xml

@@ -426,7 +426,7 @@
           <dependency groupId="com.addthis.metrics" artifactId="reporter-config3" version="3.0.0" />
           <dependency groupId="org.mindrot" artifactId="jbcrypt" version="0.3m" />
           <dependency groupId="io.airlift" artifactId="airline" version="0.6" />
-          <dependency groupId="io.netty" artifactId="netty-all" version="4.0.37.Final" />
+          <dependency groupId="io.netty" artifactId="netty-all" version="4.0.36.Final" />
           <dependency groupId="com.google.code.findbugs" artifactId="jsr305" version="2.0.2" />
           <dependency groupId="com.clearspring.analytics" artifactId="stream" version="2.5.2" />
           <dependency groupId="com.datastax.cassandra" artifactId="cassandra-driver-core" version="3.0.1" classifier="shaded">

conf/cassandra-env.ps1

@@ -350,15 +350,6 @@ Function SetCassandraEnvironment
     #$env:HEAP_NEWSIZE="800M"
     CalculateHeapSizes
 
-    # Direct memory used for native-protocol network I/O is no longer
-    # managed by the JVM. Instead, Netty allows three options to
-    # manage it via the system property io.netty.maxDirectMemory:
-    #     == 0  behavior as before, uses JVM to manage direct memory (slowest).
-    #     < 0   manages direct memory directly, max direct memory as -XX:MaxDirectMemorySize.
-    #     > 0   manages direct memory directly, max direct memory as specified.
-    #           Note, that appreviations like 2g or 500m are NOT accepted.
-    #$env:JVM_OPTS="$env:JVM_OPTS -Dio.netty.maxDirectMemory=2147483648"
-
     ParseJVMInfo
 
     # We only set -Xms and -Xmx if they were not defined on jvm.options file

conf/cassandra-env.sh

@@ -167,15 +167,6 @@ USING_G1=$?
 # Set this to control the amount of arenas per-thread in glibc
 #export MALLOC_ARENA_MAX=4
 
-# Direct memory used for native-protocol network I/O is no longer
-# managed by the JVM. Instead, Netty allows three options to
-# manage it via the system property io.netty.maxDirectMemory:
-#     == 0  behavior as before, uses JVM to manage direct memory (slowest).
-#     < 0   manages direct memory directly, max direct memory as -XX:MaxDirectMemorySize.
-#     > 0   manages direct memory directly, max direct memory as specified.
-#           Note, that appreviations like 2g or 500m are NOT accepted.
-#export JVM_OPTS="$JVM_OPTS -Dio.netty.maxDirectMemory=2147483648"
-
 # only calculate the size if it's not set manually
 if [ "x$MAX_HEAP_SIZE" = "x" ] && [ "x$HEAP_NEWSIZE" = "x" -o $USING_G1 -eq 0 ]; then
     calculate_heap_sizes