awk: use awkgram.tab.h consistently
yacc makes awkgram.h. However, one true awk includes awkgram.tab.h, so
we link to for the builds. Make sure that we consistently link to it.
Also, restore the awkgram.tab.h dependency to maketab. It should not
have been deleted, despite apparently making meta build on stable/12
work. The important missing arc was proctab.c's dependence on
MFC After: 1 day (build breakage)
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