build: Bump Meson dependency to 1.4.0

Meson 1.5.1 is available in the fd.o SDK and in Debian testing, so the
glib Meson policy says we can update.  Update the minimum only as far as
1.4.0 because we don't yet have a need for 1.5.0.

This allows us to:

- Use file.full_path() to avoid deprecation warnings on str.format(file).
- Set c_std=gnu99,c99 to avoid deprecation warnings with gnu99 on MSVC.

Update all the CI builds to use the latest 1.4.x patch release, 1.4.2.

The FreeBSD runner cannot be updated via `gitlab-ci.yml`, so will be
broken for now.

Similarly, the macOS build will not work unless `-Dc_std=gnu99` is
specified at configure time, due to
https://github.com/mesonbuild/meson/issues/13639.

girepository/introspection/meson.build

@@ -242,14 +242,14 @@ gio_gir_args = [
 if host_system == 'windows'
   gio_gir_sources += [ gio_win32_include_headers, win32_sources ]
   foreach h: gio_win32_include_headers
-    gio_gir_args += '--c-include=@0@'.format(h)
+    gio_gir_args += '--c-include=' + h.full_path()
   endforeach
   gio_gir_packages += 'gio-windows-2.0'
   gio_gir_args += '--pkg=gio-windows-2.0'
 else
   gio_gir_sources += [ gio_unix_include_headers, unix_sources ]
   foreach h: gio_unix_include_headers
-    gio_gir_args += '--c-include=@0@'.format(h)
+    gio_gir_args += '--c-include=' + h.full_path()
   endforeach
   gio_gir_packages += 'gio-unix-2.0'
   gio_gir_args += '--pkg=gio-unix-2.0'
@@ -278,7 +278,7 @@ gio_gir = gnome.generate_gir(libgio,
 if host_system == 'windows'
   gio_win32_gir_c_includes = []
   foreach h: gio_win32_include_headers
-    gio_win32_gir_c_includes += '--c-include=@0@'.format(h)
+    gio_win32_gir_c_includes += '--c-include=' + h.full_path()
   endforeach
 
   gio_win32_gir = gnome.generate_gir(libgio,
@@ -308,7 +308,7 @@ if host_system == 'windows'
 else
   gio_unix_gir_c_includes = []
   foreach h: gio_unix_include_headers
-    gio_unix_gir_c_includes += '--c-include=@0@'.format(h)
+    gio_unix_gir_c_includes += '--c-include=' + h.full_path()
   endforeach
 
   gio_unix_gir = gnome.generate_gir(libgio,