Fix how environment variables are specified for spawn.
* src/gpgrt-int.h (_gpgrt_spawn_actions_set_envvars) [HAVE_W32_SYSTEM]: Assume use with GetEnvironmentStrings. (_gpgrt_spawn_actions_set_environ) [!HAVE_W32_SYSTEM]: New. * src/spawn-posix.c: Follow the change. * src/spawn-w32.c: Can specify envvars now.
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>