* cygwin.din (sys_sigabbrev): Add this here.

* dcrt0.cc (__argc,__argv,_check_for_executable): Remove dllexport decoration
since it is already handled in cygwin.din.
* errno.cc (_sys_errlist): Ditto.
* strsig.cc (sys_sigabbrev): Ditto.
* include/cygwin/signal.h: Protect use of dllimport when __INSIDE_CYGWIN__.
* libc/getopt.c: Revert previous changes.  Define __INSIDE_CYGWIN__.

winsup/cygwin/cygwin.din

@@ -25,6 +25,7 @@ reent_data DATA
 sys_errlist = _sys_errlist DATA
 _sys_errlist DATA
 sys_nerr = _sys_nerr DATA
+sys_sigabbrev DATA
 _sys_nerr DATA
 _timezone DATA
 _tzname DATA