math: make RATIONAL tristate

Patch series "math: RATIONAL and RATIONAL_KUNIT_TEST improvements".

This series makes the RATIONAL symbol tristate, so it is not forced
builtin if all users are modular, and makes the RATIONAL_KUNIT_TEST depend
on RATIONAL, to avoid enabling RATIONAL if there are no real users.

This patch (of 2):

All but one symbols that select RATIONAL are tristate, but RATIONAL itself
is bool. Change it to tristate, so the rational fractions support code
can be modular if no builtin code relies on it.

Link: https://lkml.kernel.org/r/[e-mail]
Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: Geert Uytterhoeven <[e-mail]>
Reviewed-by: Andy Shevchenko <[e-mail]>
Cc: Trent Piepho <[e-mail]>
Cc: Colin Ian King <[e-mail]>
Cc: Brendan Higgins <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

lib/math/Kconfig

···
 	  If unsure, say N.
 
 config RATIONAL
-	bool
+	tristate

lib/math/rational.c

···
 #include <linux/export.h>
 #include <linux/minmax.h>
 #include <linux/limits.h>
+#include <linux/module.h>
 
 /*
  * calculate best rational approximation for a given fraction
···
 }
 
 EXPORT_SYMBOL(rational_best_approximation);
+
+MODULE_LICENSE("GPL v2");