I didn't tell the whole story, I actually had this
<postinstallScriptlet>
<script>cd /usr/lib64; ln -s libodbccr.so.1.0.0 libodbccr.so</script>
<script>echo "Finished Script"</script>
</postinstallScriptlet>
With postinstallScriptlet only the LAST script is executed, so I had to change it, like this
<postinstallScriptlet>
<script>
cd /usr/lib64; \
ln -s libodbccr.so.1.0.0 libodbccr.so<; \
echo "Finished Script"
</script>
</postinstallScriptlet>