docker: fix failing valgrind runs

Unless ulimit -n is set, I get errors such as this from valgrind:

    Assertion 'newfd >= VG_(fd_hard_limit)' failed.

I don't know and don't care what this is about; settings ulimit -n to
something else seems to do the trick. For reference, this can be used:

    https://www.mail-archive.com/kde-bugs-dist@kde.org/msg778326.html

1 files changed, 1 insertions, 0 deletions

diff --git a/Dockerfile b/Dockerfile
index 9de14e1..597d723 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -22,6 +22,7 @@ RUN cd -- "$src_dir" && \
         "CONFIGURATION=$CONFIGURATION" \
         "DEFAULT_HOST=$DEFAULT_HOST" \
         "INSTALL_PREFIX=$install_dir" && \
+    ulimit -n 1024 && \
     make test CONFIGURATION="$CONFIGURATION"
 
 FROM base