help building xorg-modular

[Hannes Hauswedell]

hi everyone,
i have problems building xorg-7.1... is this the place to post questions?
i could not find a forum on x.org or freedesktop.org....
anyway heres whats going wrong:
i followed the Guide on 
http://wiki.x.org/wiki/ModularDevelopersGuide#head-70b76cfa443105aa56b0c3d98615ae7d4f32c452
to build x.org with build-from-tarballs.sh, but during build it cannot find 
certain components already built... here's what i did, the directory i am 
building from is the current directory and the destination 
is /mnt/test/usr/x11r7

export PKG_CONFIG_PATH=/mnt/test/usr/x11r7lib/pkgconfig
export LD_LIBRARY_PATH=/mnt/test/usr/x11r7/lib
export PATH=/mnt/test/usr/x11r7/bin:$PATH

./build-from-tarballs.sh -m /home/user/Mesa-6.5/ -n -e /mnt/test/usr/x11r7/ > 
build.log 2>&1

many compnents are installed correctly, but somewhere at line 9,1xx in the 
logfile i get:

Building lib module component libXvMC-X11R7.1-1.0.2...
checking for a BSD-compatible install... /usr/bin/install -c
[...]
checking pkg-config is at least version 0.9.0... yes
checking for XVMC... configure: error: Package requirements (x11 xext xv 
xextproto videoproto) were not met:
No package 'xv' found
Consider adjusting the PKG_CONFIG_PATH environment variable if you
installed software in a non-standard prefix.
Alternatively, you may set the environment variables XVMC_CFLAGS
and XVMC_LIBS to avoid the need to call pkg-config.
See the pkg-config man page for more details.
***** configure failed on lib/libXvMC
make: *** Keine Targets angegeben und keine »make«-Steuerdatei gefunden. 
Schluss.
***** make failed on lib/libXvMC
make: *** Keine Regel, um »install« zu erstellen. Schluss.
***** install failed on lib/libXvMC
after that a lot of things fail with similar errors, e.g.
No package 'xbitmaps' found
No package 'libfs' found
No package 'xf86driproto' found
....

i got past many sections like this by manually installing x11proto-foobar-dev 
package on the host-OS (the one i am building from), but i think that this 
shouldnt be necessary, and that it could cause major problems, because of 
version mismatches.
what am i doing wrong?

thanks for any help!
greetings
hannes

ps: please cc to my address, thanks!