test-lib: remove unused $_x40 and $_z40 variables

These two have fallen out of use with the SHA-256 migration.

The last use of $_x40 was removed in fc7e73d (t4013: improve
diff-post-processor logic, 2020-08-21) and

The last use of $_z40 was removed in 7a868c5 (t5562: use $ZERO_OID,
2019-12-21), but it was then needlessly refactored to be hash-agnostic
in 192b517 (t: use hash-specific lookup tables to define test
constants, 2020-02-22). We can just remove it.

Signed-off-by: Ævar Arnfjörð Bjarmason <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: avar

t/test-lib.sh

@@ -534,7 +534,7 @@ SQ=\'
 # when case-folding filenames
 u200c=$(printf '\342\200\214')
 
-export _x05 _x35 _x40 _z40 LF u200c EMPTY_TREE EMPTY_BLOB ZERO_OID OID_REGEX
+export _x05 _x35 LF u200c EMPTY_TREE EMPTY_BLOB ZERO_OID OID_REGEX
 
 # Each test should start with something like this, after copyright notices:
 #
@@ -1423,10 +1423,9 @@ then
 fi
 
 # Convenience
-# A regexp to match 5, 35 and 40 hexdigits
+# A regexp to match 5 and 35 hexdigits
 _x05='[0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f]'
 _x35="$_x05$_x05$_x05$_x05$_x05$_x05$_x05"
-_x40="$_x35$_x05"
 
 test_oid_init
 
@@ -1435,7 +1434,6 @@ OID_REGEX=$(echo $ZERO_OID | sed -e 's/0/[0-9a-f]/g')
 OIDPATH_REGEX=$(test_oid_to_path $ZERO_OID | sed -e 's/0/[0-9a-f]/g')
 EMPTY_TREE=$(test_oid empty_tree)
 EMPTY_BLOB=$(test_oid empty_blob)
-_z40=$ZERO_OID
 
 # Provide an implementation of the 'yes' utility; the upper bound
 # limit is there to help Windows that cannot stop this loop from