[FS#1178] openssl build attempts to run target binaries on host

[LEDE Bugs]

The following task is now closed:

FS#1178 - openssl build attempts to run target binaries on host
User who did this - Yousong Zhou (yousong)

Reason for closing: Fixed
Additional comments about closing: Fixed now by setting CROSS_COMPILE when invoking make

More information can be found at the following URL:
https://bugs.lede-project.org/index.php?do=details&task_id=1178