[tex-live] build fails

[Sanjoy Mahajan]

> rev. 3433 and 3508 provide a workaround in web2c/xetexdir/XeTeX_ext.c  

Thanks, it now builds without error.  I tested a build on r3550 and
all was fine except for many warnings that can or maybe should be
ignored.  Some give me a bit of pause, but they are not worth trying
to fix at this late stage.  Here's an example:

gcc -DHAVE_CONFIG_H  -I. -I../../../texk/xdvik -I.. -I../../../texk/xdvik/.. -W -Wall -Wunused -I../../libs/t1lib -I../../../texk/xdvik/../../libs/t1lib -I../../libs/t1lib/../type1 -I../../../texk/xdvik/../../libs/t1lib/../type1 -DPS_GS  -I../../../texk/xdvik/gui -I../../libs/t1lib/lib/t1lib -I../kpathsea   -g -O2  -c ../../../texk/xdvik/encodings.c -o encodings.o
../../../texk/xdvik/encodings.c: In function ‘guess_encoding’:
../../../texk/xdvik/encodings.c:3471: warning: comparison is always false due to limited range of data type

[I haven't looked at the code itself to see whether there is a real
 problem.]

-Sanjoy

`Not all those who wander are lost.' (J.R.R. Tolkien)