Support git submodules in version.cc generation.

Bug: 109817231
Change-Id: I52520c01ee0e2ff452ef12e7fd49ee287d6cb369
diff --git a/Makefile.ckati b/Makefile.ckati
index 528f56f..6d45095 100644
--- a/Makefile.ckati
+++ b/Makefile.ckati
@@ -102,10 +102,10 @@
 	$(KATI_LD) $^ -o $@ $(KATI_LIBS)
 
 # Rule to generate version.cc
-KATI_GIT_DIR := $(shell git -C $(KATI_SRC_PATH) rev-parse --show-toplevel)
+KATI_GIT_DIR := $(shell cd $(KATI_SRC_PATH); realpath `git rev-parse --git-dir`)
 KATI_VERSION_DEPS :=
 ifneq ($(KATI_GIT_DIR),)
-KATI_VERSION_DEPS := $(wildcard $(KATI_GIT_DIR)/.git/HEAD $(KATI_GIT_DIR)/.git/index)
+KATI_VERSION_DEPS := $(wildcard $(KATI_GIT_DIR)/HEAD $(KATI_GIT_DIR)/index)
 endif
 ifneq ($(KATI_VERSION_DEPS),)
 KATI_VERSION := $(shell git -C $(KATI_GIT_DIR) rev-parse HEAD)