SPARK-5747: Fix wordsplitting bugs in make-distribution.sh

The `$MVN` command variable may have spaces, so when referring to it, must wrap in quotes.

Author: David Y. Ross <dyross@gmail.com>

Closes #4540 from dyross/dyr-fix-make-distribution2 and squashes the following commits:

5a41596 [David Y. Ross] SPARK-5747: Fix wordsplitting bugs in make-distribution.sh

make-distribution.sh

@@ -98,9 +98,9 @@ done
 if [ -z "$JAVA_HOME" ]; then
   # Fall back on JAVA_HOME from rpm, if found
   if [ $(command -v  rpm) ]; then
-    RPM_JAVA_HOME=$(rpm -E %java_home 2>/dev/null)
+    RPM_JAVA_HOME="$(rpm -E %java_home 2>/dev/null)"
     if [ "$RPM_JAVA_HOME" != "%java_home" ]; then
-      JAVA_HOME=$RPM_JAVA_HOME
+      JAVA_HOME="$RPM_JAVA_HOME"
       echo "No JAVA_HOME set, proceeding with '$JAVA_HOME' learned from rpm"
     fi
   fi
@@ -113,24 +113,24 @@ fi
 
 if [ $(command -v git) ]; then
     GITREV=$(git rev-parse --short HEAD 2>/dev/null || :)
-    if [ ! -z $GITREV ]; then
+    if [ ! -z "$GITREV" ]; then
 	 GITREVSTRING=" (git revision $GITREV)"
     fi
     unset GITREV
 fi
 
 
-if [ ! $(command -v $MVN) ] ; then
+if [ ! $(command -v "$MVN") ] ; then
     echo -e "Could not locate Maven command: '$MVN'."
     echo -e "Specify the Maven command with the --mvn flag"
     exit -1;
 fi
 
-VERSION=$($MVN help:evaluate -Dexpression=project.version 2>/dev/null | grep -v "INFO" | tail -n 1)
-SPARK_HADOOP_VERSION=$($MVN help:evaluate -Dexpression=hadoop.version $@ 2>/dev/null\
+VERSION=$("$MVN" help:evaluate -Dexpression=project.version 2>/dev/null | grep -v "INFO" | tail -n 1)
+SPARK_HADOOP_VERSION=$("$MVN" help:evaluate -Dexpression=hadoop.version $@ 2>/dev/null\
     | grep -v "INFO"\
     | tail -n 1)
-SPARK_HIVE=$($MVN help:evaluate -Dexpression=project.activeProfiles -pl sql/hive $@ 2>/dev/null\
+SPARK_HIVE=$("$MVN" help:evaluate -Dexpression=project.activeProfiles -pl sql/hive $@ 2>/dev/null\
     | grep -v "INFO"\
     | fgrep --count "<id>hive</id>";\
     # Reset exit status to 0, otherwise the script stops here if the last grep finds nothing\
@@ -147,7 +147,7 @@ if [[ ! "$JAVA_VERSION" =~ "1.6" && -z "$SKIP_JAVA_TEST" ]]; then
   echo "Output from 'java -version' was:"
   echo "$JAVA_VERSION"
   read -p "Would you like to continue anyways? [y,n]: " -r
-  if [[ ! $REPLY =~ ^[Yy]$ ]]; then
+  if [[ ! "$REPLY" =~ ^[Yy]$ ]]; then
     echo "Okay, exiting."
     exit 1
   fi
@@ -232,7 +232,7 @@ cp -r "$SPARK_HOME/ec2" "$DISTDIR"
 if [ "$SPARK_TACHYON" == "true" ]; then
   TMPD=`mktemp -d 2>/dev/null || mktemp -d -t 'disttmp'`
 
-  pushd $TMPD > /dev/null
+  pushd "$TMPD" > /dev/null
   echo "Fetching tachyon tgz"
 
   TACHYON_DL="${TACHYON_TGZ}.part"
@@ -259,7 +259,7 @@ if [ "$SPARK_TACHYON" == "true" ]; then
   fi
 
   popd > /dev/null
-  rm -rf $TMPD
+  rm -rf "$TMPD"
 fi
 
 if [ "$MAKE_TGZ" == "true" ]; then