update(ci): allow for submodule not be cloned

If this reposiroty is not cloned with '--recursive', the ci subdmoudle
will not be prenset which will result in any invocation of make to fail.
This modification allows that if the ci submodule is not present, it
will simply be ignored and typical make calls for building the
hypervisor will continue normally.

Signed-off-by: Jose Martins <josemartins90@gmail.com>

Makefile

@@ -47,7 +47,7 @@ scripts_dir:=$(cur_dir)/scripts
 ci_dir:=$(cur_dir)/ci
 src_dirs:=
 
-include $(ci_dir)/ci.mk
+-include $(ci_dir)/ci.mk
 
 targets:=$(MAKECMDGOALS)
 ifeq ($(targets),)
@@ -327,6 +327,8 @@ clean:
 
 # Instantiate CI rules
 
+ifneq ($(wildcard $(ci_dir)/ci.mk),)
+
 all_files= $(realpath \
 	$(cur_dir)/Makefile \
 	$(call list_dir_files_recursive, $(src_dir), *) \
@@ -342,3 +344,5 @@ $(call ci, format, $(all_c_files))
 
 .PHONY: ci
 ci: license-check format-check
+
+endif