Only generate compile_commands.json if the script exists

Author: gsingh93

Makefile

@@ -178,7 +178,11 @@ linux_menuconfig:
 .PHONY: linux
 linux $(KERNEL_IMAGE): $(LINUX_CONFIG) | $(CLANG_DIR)
 	+ $(LINUX_MAKE)
+# Older versions of Linux don't have this script
+ifneq (,$(wildcard ./.env))
 	$(LINUX_SRC)/scripts/clang-tools/gen_compile_commands.py -d $(LINUX_OUT)
+endif
+
 
 .PHONY: linux_modules
 linux_modules $(LINUX_OUT_MODULES_DEP): $(KERNEL_IMAGE)