[Bug target/50131] Optimize x = -1 with "or" for -O

[hjl.tools at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=50131

--- Comment #1 from H.J. Lu <hjl.tools at gmail dot com> 2011-08-19 20:58:00 
UTC ---
There are 1273 "movl $0xffffffff," and 924 "movq 0xffffffffffffffff,"
in cc1plus.  This change can reduce cc1plus size by 6242 bytes.