core: New API functions gpgrt_getenv and gpgrt_setenv.
* src/gpg-error.h.in (gpgrt_getenv, gpgrt_setenv): New. (gpgrt_unsetenv): New macro. * src/gpg-error.vers, src/gpg-error.def.in: Add them. * src/visibility.c (gpgrt_getenv, gpgrt_setenv): New. * src/visibility.h: Add them. * src/sysutils.c: Include string.h and on Windows windows.h. (_gpgrt_getenv): New. (_gpgrt_setenv): New.
These functions are wrappers to cope with Windows problems. The code
is similar to what we have in GnuPG but not identical.
Requires better testing.
- Signed-off-by: Werner Koch <wk@gnupg.org>