Fix FindFreetype on Windows when FREETYPE_LIBRARY is specified
On Windows if you specify the library path using a regular Windows path with backslashes, FindFreetype announces that it found the library, however later when another library attempts to use this path you get a parse error like this:
CMake Error at /CMakeFiles/CMakeTmp/CMakeLists.txt:14 (target_link_libraries): Syntax error in cmake code at
<cmake build dir>/CMakeFiles/CMakeTmp/CMakeLists.txt:14
when parsing string
d:\git\wpe-dependencies\lib64\freetyped.lib
Invalid character escape '\g'.
The found library path should be in canonical (forward slash) format.