bug#24243: fix for pcre-jitstack failure on Mac OS X

[Jack Howarth]

The pcre-jitstack test case fails on Mac OS X due to the system base64
expecting either '-D or --decode' rather than '-d or --decode'. The
trivial fix is to use the common '--decode' option rather than '-d'...

diff -uNr grep-2.25/tests/pcre-jitstack grep-2.25-patched/tests/pcre-jitstack
--- grep-2.25/tests/pcre-jitstack       2016-01-01 17:45:41.000000000 -0500
+++ grep-2.25-patched/tests/pcre-jitstack       2016-08-16
10:53:58.000000000 -0400
@@ -17,7 +17,7 @@

 fail=0

-base64 -d >pcrejit.txt.gz <<'EOF'
+base64 --decode >pcrejit.txt.gz <<'EOF'
 H4sIAAAAAAACA+2bUU4DMQxE/7mMz5T7XwKE+IBKVLue58yk0B9EtX6xJxN7t4VaH69a6+tHrW+/
 r4e3n75KARWShSOFTtiumE3FPVyo79ATIJ0Ry0No/yXe99UIUqTGKKUzYHFJHJoaCONQDCnDSCDS
 IPAvGCVeXNsZ7lpbWFfdaZtgPos5LeK2C1TBKzD09V3HFlCOsbFT/hNbz4HzJaRjnjdam9FXw/o6