Add pulsar gc log (apache#7498)

Fixes apache#7450

### Motivation
Gc log is a useful tool to help our positioning our jvm runing situation. It can use to solve gc param is not reasonable, memory leak. I think if pulsar need this too.

conf/pulsar_env.sh

@@ -47,6 +47,15 @@ PULSAR_MEM=${PULSAR_MEM:-"-Xms2g -Xmx2g -XX:MaxDirectMemorySize=4g"}
 # Garbage collection options
 PULSAR_GC=${PULSAR_GC:-"-XX:+UseG1GC -XX:MaxGCPauseMillis=10 -XX:+ParallelRefProcEnabled -XX:+UnlockExperimentalVMOptions -XX:+DoEscapeAnalysis -XX:ParallelGCThreads=32 -XX:ConcGCThreads=32 -XX:G1NewSizePercent=50 -XX:+DisableExplicitGC -XX:-ResizePLAB"}
 
+# Garbage collection log.
+IS_JAVA_8=`java -version 2>&1 |grep version|grep '"1\.8'`
+if [ ! $IS_JAVA_8 ]; then
+  PULSAR_GC_LOG=${PULSAR_GC_LOG:-"-Xloggc:logs/pulsar_gc_%p.log -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=10 -XX:GCLogFileSize=20M"}
+else
+# After jdk 9, gc log param should config like this. Ignoring version less than jdk 8
+  PULSAR_GC_LOG=${PULSAR_GC_LOG:-"-Xlog:gc:logs/pulsar_gc_%p.log:time,uptime:filecount=10,filesize=20M"}
+fi
+
 # Extra options to be passed to the jvm
 PULSAR_EXTRA_OPTS=${PULSAR_EXTRA_OPTS:-" -Dpulsar.allocator.exit_on_oom=true -Dio.netty.recycler.maxCapacity.default=1000 -Dio.netty.recycler.linkCapacity=1024"}
 

conf/pulsar_tools_env.sh

@@ -48,7 +48,7 @@ PULSAR_MEM="-Xmx128m -XX:MaxDirectMemorySize=128m"
 PULSAR_GC=" -client "
 
 # Extra options to be passed to the jvm
-PULSAR_EXTRA_OPTS="${PULSAR_EXTRA_OPTS} ${PULSAR_MEM} ${PULSAR_GC} -Dio.netty.leakDetectionLevel=disabled"
+PULSAR_EXTRA_OPTS="${PULSAR_EXTRA_OPTS} ${PULSAR_MEM} ${PULSAR_GC} ${PULSAR_GC_LOG} -Dio.netty.leakDetectionLevel=disabled"
 
 # Add extra paths to the bookkeeper classpath
 # PULSAR_EXTRA_CLASSPATH=