Dpkg::Vendor::Debian: Disable thread sanitizer when address is enabled

These are mutually incompatible, prefer the address sanitizer when both
are enabled at the same time.

debian/changelog

@@ -23,6 +23,9 @@ dpkg (1.18.2) UNRELEASED; urgency=low
       File::Spec in Dpkg::Source::Package::V2.
     - Do not exclude pre-existing symlinks when unpacking the debian/ tarball
       in Dpkg::Source::Package::V2. Closes: #790073, #791535
+    - Disable the thread sanitizer when the address sanitizer is enabled
+      in Dpkg::Vendor::Debian as these are mutually incompatible, and make
+      sanitize=+all not work at all.
   * Documentation:
     - Fix grammar in dpkg-architecture(1).
       Thanks to Chris Lamb <lamby@debian.org>. Closes: #787616

scripts/Dpkg/Vendor/Debian.pm

@@ -185,6 +185,11 @@ sub _add_sanitize_flags {
     $self->_parse_feature_area('sanitize', \%use_feature);
 
     # Handle logical feature interactions.
+    if ($use_feature{address} and $use_feature{thread}) {
+        # Disable the thread sanitizer when the address one is active, they
+        # are mutually incompatible.
+        $use_feature{thread} = 0;
+    }
     if ($use_feature{address} or $use_feature{thread}) {
         # Disable leak sanitizer, it is implied by the address or thread ones.
         $use_feature{leak} = 0;