Install valgrind on deb9 for nofib

For ghc!604 (merged).

x86_64-linux-deb9/Dockerfile

@@ -22,6 +22,8 @@ RUN apt-get update -qq && apt-get install --no-install-recommends -qy \
     xutils-dev \
     # DWARF libraries
     libdw1 libdw-dev \
+    # For nofib
+    valgrind \
     # Documentation tools
     python3-sphinx texlive-xetex texlive-latex-extra texlive-binaries texlive-fonts-recommended lmodern texlive-generic-extra \
     cabal-install-2.4 ghc-8.4.4 \