Update data.table example to support opemnp

Author: gaborcsardi

examples/data.table/Dockerfile

@@ -1,4 +1,11 @@
 
-FROM rhub/r-minimal
+FROM ghcr.io/r-hub/r-minimal/r-minimal
 
-RUN installr -d -t zlib-dev data.table
+RUN echo -e 'PKG_CFLAGS+=-fopenmp\nPKG_LIBS+=-fopenmp\n' >> /tmp/Makevars && \
+    R_MAKEVARS_USER=/tmp/Makevars \
+    installr -a "libgomp zlib" -t "openmp-dev zlib-dev" -d data.table && \
+    rm /tmp/Makevars
+
+RUN R -q -e 'data.table::getDTthreads()'
+
+RUN ldd /usr/local/lib/R/library/data.table/libs/data_table.so 2> /dev/null || true