Add FC_LIKELY and FC_UNLIKELY macros
These wrap __builtin_expect where it exists.
diff --git a/src/fcint.h b/src/fcint.h
index 08a0cd6..fb173b5 100644
--- a/src/fcint.h
+++ b/src/fcint.h
@@ -58,6 +58,14 @@
#endif
#ifdef _WIN32
+#define FC_LIKELY(expr) (expr)
+#define FC_UNLIKELY(expr) (expr)
+#else
+#define FC_LIKELY(expr) (__builtin_expect (expr, 1))
+#define FC_UNLIKELY(expr) (__builtin_expect (expr, 0))
+#endif
+
+#ifdef _WIN32
# include "fcwindows.h"
typedef UINT (WINAPI *pfnGetSystemWindowsDirectory)(LPSTR, UINT);
typedef HRESULT (WINAPI *pfnSHGetFolderPathA)(HWND, int, HANDLE, DWORD, LPSTR);
