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

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