lib: Add CMD_RANGE_STR macro to command.h

Allow the auto-generation of a "<X-Y>" string for cli handline.
Where X or Y can be a #define.

CMD_RANGE_STR(LOW, HIGH) translates to:
"<4-99>"

Signed-off-by: Donald Sharp <sharpd@cumulusnetworks.com>
diff --git a/lib/command.h b/lib/command.h
index fd55f2d..6a20e23 100644
--- a/lib/command.h
+++ b/lib/command.h
@@ -459,6 +459,17 @@
 
 #endif /* VTYSH_EXTRACT_PL */
 
+/*
+ * Sometimes #defines create maximum values that
+ * need to have strings created from them that
+ * allow the parser to match against them.
+ * These macros allow that.
+ */
+#define CMD_CREATE_STR(s)  CMD_CREATE_STR_HELPER(s)
+#define CMD_CREATE_STR_HELPER(s) #s
+#define CMD_RANGE_STR(a,s) "<" CMD_CREATE_STR(a) "-" CMD_CREATE_STR(s) ">"
+
+
 /* Common descriptions. */
 #define SHOW_STR "Show running system information\n"
 #define IP_STR "IP information\n"