Add make "doc" as prerequisite to make "dist" and "dist-devel" targets
Add make "doc" as prerequisite to make "dist" and "dist-devel" targets

Otherwise, make "dist" and make "dist-devel" fails due to missing
documentation deliverables.

acenode/gambit,jasperla/gambit,thewhimer/gambit,jasperla/gambit,thewhimer/gambit,BeImprovised/gambit,jasperla/gambit,thewhimer/gambit,BeImprovised/gambit,thewhimer/gambit,acenode/gambit,thewhimer/gambit,acenode/gambit,thewhimer/gambit,BeImprovised/gambit,acenode/gambit,BeImprovised/gambit,jasperla/gambit