i used this script, a little clunky but it got the job done
```bash
for file in `find . -type f -print | grep '\.go'`; do
sed '1,/^\/\/ limitations under the License.$/d' $file > $file.tmp;
result=`cat $file.tmp`
if [[ result != "" ]]; then
gofmt $file.tmp &> /dev/null;
if [[ $? == 0 ]]; then
mv $file.tmp $file && gofmt -w $file;
else
rm $file.tmp;
fi
else
rm $file.tmp;
fi
done
```
This is sort of prototype-ish, but the idea is that we use SetMaxMapCount
from syswrap, which already exists, to let us test edge cases like
"what happens if you only sometimes have mapped data".
close files after using them if global max is passed.
I originally implemented this without the global count—just always closing files
when done with them, and reopening for new writes. This was crazy slow for that
one test that uses mustSetBits in a big loop. I modified the test to use
importRoaring and everything worked better (though much more slowly).
After adding the global counter, I ran the tests with that one test using
mustSetBits again, and the performance was similar to master. After completing
this PR, I ran the tests with the max limit set to 5—they still passed but were
much slower.
