Where a variable name consisted of an append/prepend combined with an override
and there was also an append/prepend to the variable, the override could be lost
if the override was not in OVERRIDES.
For example:
FOO = "A"
FOO_append = "B"
FOO_append_virtclass-native = "C"
could result in "AB" even though virtclass-native was in OVERRIDES.
With this patch applied, the result is "ABC" as would be expected.
The problem was the deletion of the _append/_prepend flag was happening
if *any* append/prepend was procesed, the result should really be that
it should contain any unprocessed append/prepend.
Kevin Tian deserves credit for looking into this and working out the
problem here.
Signed-off-by: Richard Purdie <rpurdie@linux.intel.com>
