scripts: add luaposix to install-deps-macos.sh

Problem: luaposix is now required for configure, but the macos install
script doesn't install it.

Install luarocks with brew and then use luarocks to install luaposix
so that configure passes checks.

Author: grondo

scripts/install-deps-macos.sh

@@ -24,6 +24,7 @@ brew install \
   hwloc \
   sqlite \
   lua \
+  luarocks \
   python3 \
   cffi \
   libyaml \
@@ -35,4 +36,7 @@ source macos-venv/bin/activate
 pip3 install setuptools
 pip3 install -r scripts/requirements-dev.txt
 
+# luaposix now required for configure:
+luarocks install luaposix
+
 echo "Now run scripts/configure-macos.sh"