crashes in `iallocate`

[sourcefrog]

It looks like this code passes 0 as the VM argument to allocCon and that causes a crash in iallocate in current Idris.

(lldb) bt
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BAD_ACCESS (code=1, address=0x180)
  * frame #0: 0x0000000100023157 example`iallocate + 100
    frame #1: 0x0000000100000f61 example`allocConF + 49
    frame #2: 0x0000000100000f20 example`idris_makeArray + 32
    frame #3: 0x000000010000a018 example`_idris_Data_46_Array_46_prim_95_makeArray + 136
    frame #4: 0x0000000100017612 example`_idris_Data_46_Array_46_IOArray_46__123_fromList_95_7_125_ + 290
    frame #5: 0x0000000100006160 example`_idris_io_95_bind + 320
    frame #6: 0x0000000100020b76 example`_idris__123_runMain_95_0_125_ + 310
    frame #7: 0x0000000100022c9e example`main + 142
    frame #8: 0x00007fff6f29a7fd libdyld.dylib`start + 1

[sourcefrog]

I guess I should use https://github.com/ejconlon/ixarray or Data.IOArray anyhow, but it seems like this is the fix:

diff --git a/Array.c b/Array.c
index b36a471..17bfb54 100644
--- a/Array.c
+++ b/Array.c
@@ -3,7 +3,7 @@

 VAL idris_makeArray(int len) {
        VAL arr;
-       allocCon(arr, 0, 0, len, 0);
+       allocCon(arr, get_vm(), 0, len, 0);
        return arr;
 }