OpenMP problem with 64-bit Rtools

Hi Radford

I've been getting pqR to work on windows systems, and in the process
have discovered various problems with R core versions of R and with
Rtools.

We happen to be working on a new version of the windows tool chain,
perhaps you are interested to test if problems still exist in the
latest versions. Find a copy of gcc-4.9.2 as well as an installer with
the latest r-devel built with this compiler here:
http://www.stat.ucla.edu/~jeroen/mingw-w64/. Note that this R
installer contains a copy of the tool chain (hence requires no
seperate 'rtools' installation).

The reason for this appears to be that the omp.h file included is
appropriate only for the 32-bit version of the openMP library.  As
far as I can see, there is no 64-bit version of this include file
in the stuff installed with Rtools.

This particular behavior exists in all builds of mingw-w64, not rtools
per se. We might get a better answer in the mingw-w64-public mailing
list.