Merge branch 'js/gcc-8-and-9' into maint

Code clean-up for new compilers. The 'kwset' one may get a wholesale replacement, either with new version of kwset from upstream or removal of its users, but in the meantime, it is probably OK to merge it down. * js/gcc-8-and-9: config: avoid calling `labs()` on too-large data type winansi: simplify loading the GetCurrentConsoleFontEx() function kwset: allow building with GCC 8 poll (mingw): allow compiling with GCC 8 and DEVELOPER=1