Increase LSAN verbosity in Travis CI builds

Its own error message recommends using these options if it fails (as it
did in one of the builds with an irreproducible crash), so try doing it.

build/tools/travis-ci.sh

@@ -73,7 +73,9 @@ case $wxTOOLSET in
         fi
 
         if [ "$wxUSE_ASAN" = 1 ]; then
-            export LSAN_OPTIONS=suppressions=$(pwd)/misc/suppressions/lsan
+            # Increase verbosity in case something goes wrong and suppress the
+            # known leaks outside of wx itself that we can do nothing about.
+            export LSAN_OPTIONS=verbosity=1:log_threads=1:suppressions=$(pwd)/misc/suppressions/lsan
 
             wxASAN_CFLAGS="-fsanitize=address -fno-omit-frame-pointer"
             wxASAN_CXXFLAGS=$wxASAN_CFLAGS