bc: fix inverted POSIXness test, improve messages, commonalize message strings
function old new delta
bc_lex_token 1251 1285 +34
bc_POSIX_does_not_allow_bool_ops_this_is_bad - 25 +25
bc_POSIX_does_not_allow_empty_X_expression_in_for - 20 +20
bc_POSIX_does_not_allow - 20 +20
bc_parse_expr 2146 2151 +5
bc_num_ulong 103 92 -11
------------------------------------------------------------------------------
(add/remove: 3/0 grow/shrink: 2/1 up/down: 104/-11) Total: 93 bytes
text data bss dec hex filename
987210 485 7296 994991 f2eaf busybox_old
987084 485 7296 994865 f2e31 busybox_unstripped
^^^^^^^
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>