treewide: Fix unsafe concatenation of $LD_LIBRARY_PATH

Naive concatenation of $LD_LIBRARY_PATH can result in an empty
colon-delimited segment; this tells glibc to load libraries from the
current directory, which is definitely wrong, and may be a security
vulnerability if the current directory is untrusted.  (See #67234, for
example.)  Fix this throughout the tree.

Signed-off-by: Anders Kaseorg <andersk@mit.edu>

pkgs/development/pharo/vm/build-vm.nix

@@ -117,7 +117,7 @@ stdenv.mkDerivation rec {
     cat > "$out/bin/${cmd}" <<EOF
     #!${runtimeShell}
     set -f
-    LD_LIBRARY_PATH="\$LD_LIBRARY_PATH:$libs" exec $out/pharo "\$@"
+    LD_LIBRARY_PATH="\$LD_LIBRARY_PATH''${LD_LIBRARY_PATH:+:}$libs" exec $out/pharo "\$@"
     EOF
     chmod +x "$out/bin/${cmd}"
     ln -s ${libgit2}/lib/libgit2.so* "$out/"