tdf#105204 fix shellcheck warnings in ure/source/uno

Use $(..) instead of `..`,
double quote to prevent word splitting.

Change-Id: I80251d98e6fb27af5a18c202521050c8101131fa
Reviewed-on: https://gerrit.libreoffice.org/37465Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Chris Sherlock <chris.sherlock79@gmail.com>

ure/source/uno

@@ -26,11 +26,11 @@ for my_arg in "$@" ; do
 done
 
 # Extend the LD_LIBRARY_PATH for Java:
-epath=`dirname "$0"`
+epath=$(dirname "$0")
 if [ -x "${epath}/javaldx" ] ; then
-    jpath=`"${epath}/javaldx" $my_envargs`
+    jpath=$("${epath}/javaldx" "$my_envargs")
     if [ -n "${jpath}" ]; then
-        sd_platform=`uname -s`
+        sd_platform=$(uname -s)
         case $sd_platform in
           AIX)
             LIBPATH=${jpath}${LIBPATH:+:${LIBPATH}}