wing: Attempt to fix cross compile issues.

wing: Attempt to fix cross compile issues.
The target build inherits configure properties from the host. This results in broken compile for an ARM target and PPC host. (and other combinations as well).
This tries to fix it. However, it still is not 100% safe. However, it does work on ARM/PPC with these changes.
We should either split this into host and target packages, or run a "make clean" between the host and target parts.

git-svn-id: svn://svn.openwrt.org/openwrt/packages@23376 3c298f89-4303-0410-b956-a3cf2f4a3e73