[CMake] Problem with CHECK_FUNCTION_EXISTS and strcasecmp

[Michael Surette]

I am updating the CMake build files for a cross-platform project.  One 
of the tests is for strcasecmp for which I use CHECK_FUNCTION_EXISTS. 
If it's not found the code generates its own function by that name.

This works well with GCC under Linux, including cross-compiling with 
MinGW, as well as MinGW under Windows.

Testing this with MSVS 2008 Express under Windows XP, it fails to find 
the function but gives errors and fails when I try to build.

If I manually edit the config.h file generated by CMake so that it 
misreports that there is a strcasecmp function available it compiles well.

My conclusion is that either this function exists or a macro is defining 
it, but it's not being found by CHECK_FUNCTION_EXISTS.  I've greped 
through the header files, but find no reference to it.

How can I find this function reliably?

Mike