making refdocs buildable outside of the tree, at least for modref and traditional manual

Rev: bin/install.pike:1.121
Rev: lib/modules/Tools.pmod/Standalone.pmod/module.pike:1.21
Rev: refdoc/Makefile:1.58
Rev: refdoc/presentation/make_html.pike:1.63
Rev: src/Makefile.in:1.365
Rev: src/modules/common_module_makefile.in:1.14