crypt32: check for NULL target pointers (Coverity)

[Juan Lang]

Hi Marcus,

Ideally this patch would be accompanied by a test.  Also, this change:

@@ -212,6 +212,10 @@ static BOOL CRYPT_DecodeEnsureSpace(DWORD dwFlags,

     if (dwFlags & CRYPT_DECODE_ALLOC_FLAG)
     {
+        if (!pvStructInfo) {
+            SetLastError(ERROR_INVALID_PARAMETER);
+            return FALSE;
+        }

is a noop in all but one case:  all the callers of
CRYPT_DecodeEnsureSpace, save one, check pvStructInfo before calling
it.  It would be clearer, IMO, to change the single caller that
doesn't check pvStructInfo (CryptDecodeObjectEx) rather than adding a
check that is useless in most cases.  A similar statement applies to
the encode.c change:  just change CryptEncodeObjectEx, not
CRYPT_EncodeEnsureSpace.

Finally, please indent consistently with the rest of the file.

If you prefer, I can try to fix this.  Triaging the Coverity bugs is
probably enough work by itself, without being expected to fix them too
;-)  Thanks,
--Juan