core: New API functions gpgrt_strdup and gpgrt_strconcat.
* src/visibility.c (gpgrt_strdup): New API fucntion. (gpgrt_strconcat): New API fucntion. * src/visibility.h: Add corresponding macros. * src/gpg-error.def.in: Add them. * src/gpg-error.vers: Add them. * src/gpgrt-int.h (DIM): New macro. * src/init.c (_gpgrt_strdup): New. (_gpgrt_strconcat_core): New. (_gpgrt_strconcat): New.
- Signed-off-by: Werner Koch <wk@gnupg.org>