SPARK-5856: Launch Zinc with larger memory options.

I've seen out of memory exceptions when trying
to run many parallel builds against the same Zinc
server during packaging. We should use the same
increased memory settings we use for Maven itself.

I tested this and confirmed that the Nailgun JVM
launched with higher memory.

build/mvn

@@ -21,6 +21,8 @@
 _DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 # Preserve the calling directory
 _CALLING_DIR="$(pwd)"
+# Options used during compilation
+_COMPILE_JVM_OPTS="-Xmx2g -XX:MaxPermSize=512M -XX:ReservedCodeCacheSize=512m"
 
 # Installs any application tarball given a URL, the expected tarball name,
 # and, optionally, a checkable binary path to determine if the binary has
@@ -136,14 +138,15 @@ cd "${_CALLING_DIR}"
 # Now that zinc is ensured to be installed, check its status and, if its
 # not running or just installed, start it
 if [ -n "${ZINC_INSTALL_FLAG}" -o -z "`${ZINC_BIN} -status`" ]; then
+  export ZINC_OPTS=${ZINC_OPTS:-"$_COMPILE_JVM_OPTS"}
   ${ZINC_BIN} -shutdown
   ${ZINC_BIN} -start -port ${ZINC_PORT} \
     -scala-compiler "${SCALA_COMPILER}" \
     -scala-library "${SCALA_LIBRARY}" &>/dev/null
 fi
 
 # Set any `mvn` options if not already present
-export MAVEN_OPTS=${MAVEN_OPTS:-"-Xmx2g -XX:MaxPermSize=512M -XX:ReservedCodeCacheSize=512m"}
+export MAVEN_OPTS=${MAVEN_OPTS:-"$_COMPILE_JVM_OPTS"}
 
 # Last, call the `mvn` command as usual
 ${MVN_BIN} "$@"