Check that javadoc exist to avoid empty files.

When running `ant clean dist-dev` javadocs are empty and we should not
install them. Also if the script is run with `bash -e` flag the non zero
exit of the jar command make the entire process fail

Change-Id: I44fbebd9cd63bb484c044d6aea7e50775fe7b27e

maven/lib-gwt.sh

diff --git a/maven/lib-gwt.sh b/maven/lib-gwt.sh
index b6dac82..e8bad8c 100644
--- a/maven/lib-gwt.sh
+++ b/maven/lib-gwt.sh
@@ -67,7 +67,7 @@
   GWT_EXTRACT_DIR=$RANDOM_DIR/$GWT_EXTRACT_DIR
 
   JAVADOC_FILE_PATH=$RANDOM_DIR/gwt-javadoc.jar
-  jar cf $JAVADOC_FILE_PATH -C $GWT_EXTRACT_DIR/doc/javadoc .
+  [ -d $GWT_EXTRACT_DIR/doc/javadoc ] && jar cf $JAVADOC_FILE_PATH -C $GWT_EXTRACT_DIR/doc/javadoc .
 
   # Create a dummy javadoc JAR for JsInterop (gwt-javadoc is too heavy)
   JSINTEROP_JAVADOC_FILE_PATH=$RANDOM_DIR/jsinterop-javadoc.jar

maven/lib-maven-deploy.sh

diff --git a/maven/lib-maven-deploy.sh b/maven/lib-maven-deploy.sh
index e466417..0f2c803 100644
--- a/maven/lib-maven-deploy.sh
+++ b/maven/lib-maven-deploy.sh
@@ -31,12 +31,12 @@
   local pomFile=$1
   shift
 
-  if [ $# -ne 0 ] && [ "$1" != "" ]; then
-    local javadoc="-Djavadoc=$1"
+  if [ $# -ne 0 ] && [ -n "$1" ]; then
+    [ -f "$1" ] && local javadoc="-Djavadoc=$1"
     shift
   fi
-  if [ $# -ne 0 ] && [ "$1" != "" ]; then
-    local sources="-Dsources=$1"
+  if [ $# -ne 0 ] && [ -n "$1" ]; then
+    [ -f "$1" ] && local sources="-Dsources=$1"
     shift
   fi