Add support for Cell (requires gcc-4.2 or patches)

Originally committed as revision 9181 to svn://svn.ffmpeg.org/ffmpeg/trunk

configure

@@ -1365,6 +1365,11 @@ if test $cpu != "generic"; then
             warn_altivec disabled PPC970
             POWERPCMODE="64bits"
         ;;
+        Cell|CELL|cell)
+            add_cflags "-mcpu=cell"
+            warn_altivec disabled Cell
+            POWERPCMODE="64bits"
+        ;;
         # targets that do NOT support conditional mov (cmov)
         i[345]86|pentium|pentium-mmx|k6|k6-[23]|winchip-c6|winchip2|c3)
             add_cflags "-march=$cpu"