nix: add missing args to gcroots.sh script

This should fix the following error showing up on MacOS:
```
error: assertion ((__lessThan  0)  ((builtins).stringLength  watchmanSockPath))
failed at /Users/jenkins/repos/status-react/nix/mobile/android/watchman.nix:8:9
```
Which was caused by flags like `--argstr` not being passed.

Signed-off-by: Jakub Sokołowski <jakub@status.im>

nix/scripts/build.sh

@@ -55,7 +55,7 @@ nixOpts=(
 )
 
 # Save derivation from being garbage collected
-${GIT_ROOT}/nix/scripts/gcroots.sh "${TARGET}"
+${GIT_ROOT}/nix/scripts/gcroots.sh "${TARGET}" "${@}"
 
 # Run the actual build
 echo "Running: nix-build "${nixOpts[@]}" "${@}" default.nix"

nix/scripts/gcroots.sh

@@ -1,6 +1,6 @@
 #!/usr/bin/env bash
 
-set -Eeu
+set -Ee
 
 _NIX_GCROOTS="${_NIX_GCROOTS:-/nix/var/nix/gcroots/per-user/${USER}/status-react}"
 
@@ -9,6 +9,7 @@ source "${GIT_ROOT}/nix/scripts/source.sh"
 source "${GIT_ROOT}/scripts/colors.sh"
 
 TARGET="${1}"
+shift
 if [[ -z "${TARGET}" ]]; then
     echo -e "${RED}No target specified for gcroots.sh!${RST}" >&2
     exit 1
@@ -18,4 +19,4 @@ fi
 # This prevents it from being removed by 'gc-collect-garbage'.
 nix-instantiate --attr "${TARGET}" \
     --add-root "${_NIX_GCROOTS}/${TARGET}" \
-    "${GIT_ROOT}/default.nix" >/dev/null
+    "${@}" "${GIT_ROOT}/default.nix" >/dev/null