CONFIG_FEATURE_USE_BSS_TAIL code was aliasing bb_common_bufsiz1 to _end.
This is unreliable: _end may be not sufficiently aligned.
Change code to simply enlarge COMMON_BUFSIZE when we detect that _end
has significant amount of space to the end of page.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
5b8c89d1f2