Backported change from 2.5 into 2.1 in sg_utf8.c.  Use SG_CONTEXT__HAS_ERR() macro.
W8408 Make SG_utf8__import_buffer() use explicitly signed/unsigned character pointers.
added -fsigned-char to makefile. W8408
merged signed-char and sg_utf8__import_buffer changes into master (2.1).
When user interaction with the OS X keychain is no allowed, fall back to the password prompt
disabled u0040_unc due to its dependancy on our local LAN
merge