Fix the non-Linux case so it at least compiles.

--- webkitgtk-2.48.1/Source/WTF/wtf/glib/FileSystemGlib.cpp.orig
+++ webkitgtk-2.48.1/Source/WTF/wtf/glib/FileSystemGlib.cpp
@@ -82,7 +82,9 @@
     ssize_t result = readlink("/proc/curproc/file", readLinkBuffer, PATH_MAX);
     if (result == -1)
         return { };
-    return CString(readLinkBuffer, result);
+WTF_ALLOW_UNSAFE_BUFFER_USAGE_BEGIN
+    return CString({ readLinkBuffer, static_cast<size_t>(result) });
+WTF_ALLOW_UNSAFE_BUFFER_USAGE_END
 }
 #elif OS(WINDOWS)
 CString currentExecutablePath()