ada: Simplify handling of VxWorks-specific error codes for ENOENT
These error codes were defined on older versions of VxWorks (5, 6, 7
SR0540) and now they are either not defined or they fallback to
ENOENT. To handle these cases without using complex tests against
vxworks versions, leverage on __has_include and provide a fallback to
ENOENT if these error codes are not defined.
gcc/ada/
* sysdep.c (S_dosFsLib_FILE_NOT_FOUND, S_nfsLib_NFSERR_NOENT):
New macros, falback to ENOENT when not already defined.
(__gnat_is_file_not_found_error): Use these new macros to remove
tests against VxWorks flavors.