common: Use default_errsource for call-gpg and exectool.
* common/call-gpg.c (my_error_from_syserror, my_error_from_errno): New. Use these wrappers. * common/exectool.c (my_error_from_syserror): New. Use these wrappers.
Function in common should use the error source of the component which
links them. The global variable DEFAULT_ERRSOURCE is set early by
each component to make this possible.
- Signed-off-by: Werner Koch <wk@gnupg.org>