The android message analyzer makes a comment that accepts information and warning tags in your Android.mk.
For example, if you want to print the value of an internal variable:
LOCAL_CFLAGS := -DHAVE_ERRNO_H -g
$(info value of LOCAL_CFLAGS is: $(LOCAL_CFLAGS))
.
$(warning value of LOCAL_CFLAGS is: $(LOCAL_CFLAGS))
$(error value of LOCAL_CFLAGS is: $(LOCAL_CFLAGS))
.