lib/test_string.c: move string selftest in the Runtime Testing menu

STRING_SELFTEST is presented in the "Library routines" menu.  Move it in
Kernel hacking > Kernel Testing and Coverage > Runtime Testing together
with other similar tests found in lib/

	--- Runtime Testing
	<*>   Test functions located in the hexdump module at runtime
	<*>   Test string functions (NEW)
	<*>   Test functions located in the string_helpers module at runtime
	<*>   Test strscpy*() family of functions at runtime
	<*>   Test kstrto*() family of functions at runtime
	<*>   Test printf() family of functions at runtime
	<*>   Test scanf() family of functions at runtime

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Matteo Croce <[email protected]>
Cc: Peter Rosin <[email protected]>
Cc: Geert Uytterhoeven <[email protected]>
Cc: Randy Dunlap <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: teknoraver

lib/Kconfig

@@ -683,9 +683,6 @@ config PARMAN
 config OBJAGG
 	tristate "objagg" if COMPILE_TEST
 
-config STRING_SELFTEST
-	tristate "Test string functions"
-
 endmenu
 
 config GENERIC_IOREMAP

lib/Kconfig.debug

@@ -2180,6 +2180,9 @@ config ASYNC_RAID6_TEST
 config TEST_HEXDUMP
 	tristate "Test functions located in the hexdump module at runtime"
 
+config STRING_SELFTEST
+	tristate "Test string functions at runtime"
+
 config TEST_STRING_HELPERS
 	tristate "Test functions located in the string_helpers module at runtime"