ccls: init at 0.20181225

- tested with [emacs](https://dl.thalheim.io/kdh-PwxzlwGKTEl1_NpTzg/2019-01-13-190156_1920x1080_scrot.png)
and vim.
- wrapped to pick up our cc wrapper environment -> works perfectly in nix-shell

pkgs/development/tools/misc/ccls/wrapper

@@ -0,0 +1,12 @@
+#! @shell@ -e
+
+initString="--init={\"clang\":{\"extraArgs\": [@standard_library_includes@"
+
+if [ "${NIX_CFLAGS_COMPILE}" != "" ]; then
+  read -a cflags_array <<< ${NIX_CFLAGS_COMPILE}
+  initString+=$(printf ', \"%s\"' "${cflags_array[@]}")
+fi
+
+initString+="]}}"
+
+exec -a "$0" "@out@/bin/@wrapped@" "${initString}" "${extraFlagsArray[@]}" "$@"