Add executable flags via .gitattributes so release artifacts have executable bits
Add executable flags via .gitattributes so release artifacts have executable bits

executable is a non-standard bit that is used by
https://github.com/vlsi/vlsi-release-plugins/tree/master/plugins/stage-vote-release-plugin

It enables to create the appropriate archives even in case the filesystem
does not support executable file attributes.

apache/calcite,jcamachor/calcite,datametica/calcite,jcamachor/calcite,julianhyde/calcite,apache/calcite,googleinterns/calcite,vlsi/calcite,jcamachor/calcite,datametica/calcite,vlsi/calcite,datametica/calcite,vlsi/calcite,looker-open-source/calcite,looker-open-source/calcite,vlsi/calcite,looker-open-source/calcite,apache/calcite,looker-open-source/calcite,datametica/calcite,vlsi/incubator-calcite,apache/calcite,datametica/calcite,looker-open-source/calcite,vlsi/calcite,looker-open-source/calcite,julianhyde/calcite,vlsi/incubator-calcite,julianhyde/calcite,apache/calcite,vlsi/calcite,googleinterns/calcite,googleinterns/calcite,googleinterns/calcite,apache/calcite,jcamachor/calcite,julianhyde/calcite,julianhyde/calcite,googleinterns/calcite,datametica/calcite,julianhyde/calcite,googleinterns/calcite,jcamachor/calcite,jcamachor/calcite