eina: add MIN/MAX redefine as we use it everywhere.

This is done on an attempt to permanently fix our Windows port. Windows
doesn't have MIN/MAX, so we should always do a ifndef/define in every
piece of code that use it. Of course we always forget and it take times
to notice and fix. We have over the year added it in many private
headers, but as the issue continue to raise again and again, I prefer
to get this fixed in our main header.

src/lib/eina/eina_cpu.h

@@ -122,6 +122,14 @@ static inline unsigned int eina_swap32(unsigned int x);
  */
 static inline unsigned long long eina_swap64(unsigned long long x);
 
+#ifndef MIN
+# define MIN(x, y)          (((x) > (y)) ? (y) : (x))
+#endif
+
+#ifndef MAX
+# define MAX(x, y)          (((x) > (y)) ? (x) : (y))
+#endif
+
 #include "eina_inline_cpu.x"
 
 /**