build-aux: Sync manywarnings.m4 to latest Gnulib version

* build-aux/manywarnings.m4: Likewise.
maint: Sync macros.h to latest version

* lib/macros.h: Likewise.
maint: Rename 'range' to 'clamp' due to last commit

* nclua/canvas.c: Likewise.
* nclua/event/socket.c: Likewise.
* tests/tests0.c: Likewise.