hexdump: introduce test suite

Test different scenarios of function calls located in lib/hexdump.c.

Currently hex_dump_to_buffer() is only tested and test data is provided
for little endian CPUs.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index e5ea3ab..79a9bb6 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1580,6 +1580,9 @@
 
 	  If unsure, say N.
 
+config TEST_HEXDUMP
+	tristate "Test functions located in the hexdump module at runtime"
+
 config TEST_STRING_HELPERS
 	tristate "Test functions located in the string_helpers module at runtime"