GHA/configure-vs-cmake: add Windows build, fix issues

- configure: disable pthreads by default on Windows.
- configure: disable detecting `fseeko()` on Windows.
  (It exists in mingw-w64 2.0.0 and newer, but it's permanently ignored
  in CMake, as this function is never necessary on Windows.)
- extend existing exceptions with their Windows variants.
- `lib/formdata.c`: prioritize `_fseeki64()` over `fseeko()`.
  To reduce the difference between Windows builds, which now all use
  `_fseeki64()`.
- cmake: perm-enable `HAVE_DIRENT_H` and `HAVE_OPENDIR` for mingw-w64,
  to match configure.
  Follow-up to bfe54b0e88 #13137
  This in theory could make the dir listing feature work in mingw-w64
  build, but in my tests (on WINE) it failed at the preceding `open()`
  call.
- cmake: perm-enable `HAVE_STRINGS_H` and `HAVE_UTIME_H` for mingw-w64,
  to match configure. (They are wrappers and make no difference in the build.)

Also:
- configure: sync `USE_MANUAL` macro with cmake, by only setting it for
  `src`. Drop checker exception.
- CI: use `--disable-dependency-tracking` in existing jobs.
- CI: install packages before git checkout, in existing jobs.

Closes #14678

src/Makefile.am

@@ -113,6 +113,7 @@ CS_ = $(CS_0)
 
 if USE_MANUAL
 # Here are the stuff to create a built-in manual
+AM_CPPFLAGS += -DUSE_MANUAL
 
 $(ASCIIPAGE):
 	cd $(top_builddir)/docs && $(MAKE)