patch makes sure that files included using ".include <bsd.own.mk>" are
really looked for in the system make file directory or in the specified -m
paths instead of allways looking in the other -I and .PATH specified paths
... This speeds up the make a few procents at times for all the system make
files are now found directly instead of searching several paths, saving a
lot of stat() calls.
The number of stat calls is still exorbirant hight though... 910 or so for
making `make' alone ....
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