where is strstri in script.cpp defined?

[PerditionC]

I finally compiled a MinGW build that correctly handled user variables (the .ndata section originally was placed before the imports causing fun havoc), and I am updating my source from a few weeks back before submitting a patch. However, script.cpp now seems to make use of strstri, but I can't seem to find where the function/macro is defined.
I'm probably just overlooking it, but would someone please point out where in the source it is defined.

Thanks,
Jeremy