xxd -r: without -p, stop at more than one whitespace, closes 14786

function                                             old     new   delta
xxd_main                                             888    1076    +188

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

testsuite/xxd.tests

@@ -37,4 +37,13 @@ testing 'xxd -p -r' \
 	'' \
 	'30313233343536373736353433323130 30313233343536373736353433323130'
 
+testing 'xxd -r skips leading whitespace and truncates at two spaces' \
+	'xxd -r' \
+	'0123456789:;<=>?@' \
+	'' \
+"\
+   00000000: 3031 3233 3435 3637 3839 3a3b 3c3d 3e3f  0123456789:;<=>?
+	00000010: 40                                       @
+"
+
 exit $FAILCOUNT