[PATCH 2/6] Committed: Remove __need macros from signal.h.

[Joseph Myers]

The basic issue behind this build breakage is: bits/siginfo-arch.h uses 
#undef/#define to make adjustments to defaults from more than one other 
bits/ header (so it's included from bits/types/siginfo_t.h to adjust some 
defines from there, but also from bits/siginfo-consts.h to adjust some 
defines from there).  For this to work, however, it can only safely be 
included after both sets of defaults have been defined.  I think either it 
needs to be split up into two headers, each one only included after the 
relevant defaults have been defined, or the defaults all need to come in 
one place.  (One possibility for the split would be a header that defines 
only __SI_ASYNCIO_AFTER_SIGIO, at which point you don't need a #undef, 
just a version that defines it to 1 and a version that defines it to 0.)

-- 
Joseph S. Myers
joseph@codesourcery.com