Introduce shared/defines.h to collect commonly used macros. For now

it defines min() / max() macros.

shared/defines.h

@@ -0,0 +1,23 @@
+/** \file shared/defines.h
+ * Define macros commonly used in other parts of LCDproc.
+ */
+
+/*-
+ * This file is part of LCDproc.
+ *
+ * This file is released under the GNU General Public License.
+ * Refer to the COPYING file distributed with this package.
+ */
+
+#ifndef SHARED_DEFINES_H
+#define SHARED_DEFINES_H
+
+/* Define min() and max() */
+#ifndef min
+# define min(a,b) (((a) < (b)) ? (a) : (b))
+#endif
+#ifndef max
+# define max(a,b) (((a) > (b)) ? (a) : (b))
+#endif
+
+#endif