testsuite/sha1sum.tests: fix false positive failure

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

testsuite/sha1sum.tests

@@ -4,10 +4,12 @@
 
 # testing "test name" "cmd" "expected result" "file input" "stdin"
 >EMPTY
+optional FEATURE_MD5_SHA1_SUM_CHECK
 testing "sha1sum: one-space separated input for -c" \
 	'echo "da39a3ee5e6b4b0d3255bfef95601890afd80709 EMPTY" | sha1sum -c' \
 	"EMPTY: OK\n" \
 	"" ""
+SKIP=
 rm EMPTY
 
 . ./md5sum.tests sha1sum d41337e834377140ae7f98460d71d908598ef04f