Enable CrossGen tests

parent #276 

Verified with "build.cmd verify" and crossgen generated all dlls successfully (although I got a bunch of warnings during generation).
When we execute
```batchfile
cmd /C "path/to/k" crossgen --in "path/to/target"
```
Since the text passed to cmd.exe has a leading double quote and a trailing double quote, cmd.exe strip the leading quote and remove trailing quote before doing any further processing (see `cmd /?` page 2).
So, in the example above, cmd.exe thinks we are passing
```
path/to/k" crossgen --in "path/to/target
```
as a SINGLE long argument enclosed by a pair of double quotes,
instead of the following four arguments
```
"path/to/k" crossgen --in "path/to/target"
```
We can resolve the problem by changing the command to
```batchfile
cmd /C path/to/k crossgen --in "path/to/target"
```
i.e. removing the double quotes around first argument.
However, it introduces a new problem:
if `path/to/k` contains spaces, it breaks the command if we don't double quote it.