HADOOP-18198. add -mvnargs option to create-release command line (#4239)

This allows for builds to be run with options like
--mvnargs="-Dhttp.keepAlive=false -Dmaven.wagon.http.pool=false"

Contributed by Ayush Saxena.

Change-Id: I0e3d421da13bf0bc32cbbfbfb2c428828bdbb84c

dev-support/bin/create-release

@@ -293,6 +293,7 @@ function usage
   echo "--security              Emergency security release"
   echo "--sign                  Use .gnupg dir to sign the artifacts and jars"
   echo "--version=[version]     Use an alternative version string"
+  echo "--mvnargs=[args]        Extra Maven args to be provided when running mvn commands"
 }
 
 function option_parse
@@ -347,6 +348,9 @@ function option_parse
       --version=*)
         HADOOP_VERSION=${i#*=}
       ;;
+      --mvnargs=*)
+        MVNEXTRAARGS=${i#*=}
+      ;;
     esac
   done
 
@@ -413,6 +417,9 @@ function option_parse
       MVN_ARGS=("-Dmaven.repo.local=${MVNCACHE}")
     fi
   fi
+  if [ -n "$MVNEXTRAARGS" ]; then
+    MVN_ARGS+=("$MVNEXTRAARGS")
+  fi
 
   if [[ "${SECURITYRELEASE}" = true ]]; then
     if [[ ! -d "${BASEDIR}/hadoop-common-project/hadoop-common/src/site/markdown/release/${HADOOP_VERSION}" ]]; then