[Review Required][UpdatedPR#9472] Adding more file formats to license_header.py (.m, .mk, .R, .cfg) #9472

[mbaijal]

Fixing Apache RAT failures - Part 1##

Updated PR #9472
PLEASE HELP REVIEW! @hen @bhavinthaker @gautamkmr @marcoabreu @KellenSunderland
Added some file formats to the license_header.py script and then added the Apache license to the files that were failing the updated check.

For further details, Refer to this wiki -
https://cwiki.apache.org/confluence/display/MXNET/MXNet+Source+Licenses

Checklist

Essentials

• Passed code style checking (make lint)
• Changes are complete (i.e. I finished coding on this PR)
• To the my best knowledge, examples are either not affected by this change, or have been fixed to be compatible with this change

Changes

• The main change is adding this to the license_header.py - '.m':'%', '.R':'#', '.mk':'#' , '.cfg':'#'
• Added Apache License Header to all .R, .mk , .m , .cfgfiles using the license_header.py script

Please Review the following -

• correct comment markers are used for the new formats
• It is ok to add a license to these files (nothing will break)
• the updated files do fall under the Apache license
• Please help make sure that NO CODE has been affected in this PR (only blank spaces and comments)

Comments -

1. Also To be added to the script (in a separate PR after release)

• .proto
• Makefile
• .pyx
• .properties
• .in

2. Removing whitespaces from these files will be a separate PR.