* For CRAN submission, remove all #pragma's that suppress compiler warnings
A few headers in dmlc-core contain #pragma's that disable compiler warnings,
which is against the CRAN submission policy. Fix the problem by removing
the offending #pragma's as part of the command `make Rbuild`.
This addresses issue #3322.
* Fix script to improve Cygwin/MSYS compatibility
We need this to pass rmingw CI test
* Remove remove_warning_suppression_pragma.sh from packaged tarball
