Wait a bit before invoking make install

The same docker build sometimes works and sometimes doesn't. I have a
hunch that there is some timing involved here. Maybe the build command
isn't quite finished yet before that install command is invoked.

As a workaround we make the install command wait a little before
starting. This seems to help.

rockspecs/lua-louis-scm-0.rockspec

@@ -19,5 +19,5 @@ build = {
       "examples"
    },
    build_command = "LUA=$(LUA) CPPFLAGS=-I$(LUA_INCDIR) ./configure --prefix=$(PREFIX) --libdir=$(LIBDIR) --datadir=$(LUADIR) && make clean && make",
-   install_command = "make install"
+   install_command = "sleep 1 && make install"
 }