Ensure that recursive QMAKE_EXTRA_TARGETS use the correct makefile
Recursive QMAKE_EXTRA_TARGETS were omitting the `-f' option to make.
This would break in the case where the correct makefile was not named
`Makefile'. The included autotest demonstrates the problem.
Note that this was fixed for normal targets back in 2005
by
faac7bd178654fd67a6f3f9cf4f6f2605071448d (p4 202370), but was not
fixed for extra targets.
Reviewed-by: ossi
(cherry picked from commit
96a3bf7a8bbc1e5361e16cbeeceb4be674b88c30)