tools: check for libaio unless user has configured CONFIG_SYSTEM_LIBAIO=n

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>

tools/check/Makefile

@@ -6,6 +6,7 @@ export PYTHON
 export LIBXENAPI_BINDINGS
 export CHECK_INCLUDES
 export CHECK_LIB
+export CONFIG_SYSTEM_LIBAIO
 
 .PHONY: all install
 all install: check-build