[PATCH] make it compile with gcc 4.3

This patch (relative to hg from 2 days ago + my patch to switch it to b23) 
makes icedtea build with gcc 4.3.

Some chunks are fairly crappy (just getting rid of -Werror because openjdk 
code is nowhere near clean enough to compile with -Werror on gcc 4.3 --- lots 
of warnings saying the likes of
"cast from short to unsigned int:3 may change value"), the other bits are 
mostly adding missing includes (e.g. libstdc++'s <string> no longer includes 
<cstring>/<string.h>, causing gcc to complain about lack of memcpy/strlen/... 
prototypes.

Regards,
bero