Dpkg::Vendor::Debian: Do not disable stack-protector on arm64

The toolchain supports it now on arm64.

Closes: #751032

Signed-off-by: Guillem Jover <guillem@debian.org>

debian/changelog

@@ -15,6 +15,9 @@ dpkg (1.17.11) UNRELEASED; urgency=low
   * Fix file triggers/Unincorp descriptor leak on subprocesses. Regression
     introduced with the initial triggers implementation in dpkg 1.14.17.
     Closes: #751021
+  * Do not disable the stack-protector build flags on arm64 in Debian and
+    derivatives, the toolchain supports them now.
+    Thanks to Adam Conrad <adconrad@debian.org>. Closes: #751032
 
   [ Updated programs translations ]
   * Danish (Joe Dalton). Closes: #754127

scripts/Dpkg/Vendor/Debian.pm

@@ -122,8 +122,8 @@ sub add_hardening_flags {
 	#  (#574716).
 	$use_feature{pie} = 0;
     }
-    if ($cpu =~ /^(?:ia64|alpha|mips|mipsel|hppa|arm64)$/ or $arch eq 'arm') {
-	# Stack protector disabled on ia64, alpha, arm64, mips, mipsel, hppa.
+    if ($cpu =~ /^(?:ia64|alpha|mips|mipsel|hppa)$/ or $arch eq 'arm') {
+	# Stack protector disabled on ia64, alpha, mips, mipsel, hppa.
 	#   "warning: -fstack-protector not supported for this target"
 	# Stack protector disabled on arm (ok on armel).
 	#   compiler supports it incorrectly (leads to SEGV)