@curaga: Did you think about applying the mesa-7.1-link-shared.patch as it is used for example in Fedora? It reduces the size of the mesa modules extremely by extracting most of the code into a shared libdricore.so, some time ago I already managed to do that on my own for Xorg-7.5, so it's at least possible IMHO...
Fedora example:
$ ls -l /usr/lib64/dri/
-rwxr-xr-x. 1 root root  515920  2. Mar 06:04 i915_dri.so
-rwxr-xr-x. 1 root root  563152  2. Mar 06:04 i965_dri.so
-rwxr-xr-x. 1 root root 2163544  2. Mar 06:04 libdricore.so
-rwxr-xr-x. 1 root root  305424  2. Mar 06:04 mga_dri.so
-rwxr-xr-x. 1 root root  212336  2. Mar 06:04 r128_dri.so
-rwxr-xr-x. 1 root root  410440  2. Mar 06:04 r200_dri.so
-rwxr-xr-x. 1 root root  396344  2. Mar 06:04 r300_dri.so
-rwxr-xr-x. 1 root root  341320  2. Mar 06:04 r600_dri.so
-rwxr-xr-x. 1 root root  371400  2. Mar 06:04 radeon_dri.so
-rwxr-xr-x. 1 root root  245088  2. Mar 06:04 savage_dri.so
-rwxr-xr-x. 1 root root   49008  2. Mar 06:04 swrast_dri.so
-rwxr-xr-x. 1 root root  284784  2. Mar 06:04 tdfx_dri.so
-rwxr-xr-x. 1 root root  228064  2. Mar 06:04 unichrome_dri.so
$ du -h /usr/lib64/dri
5,9M	/usr/lib64/dri
[edit]Added patch to attachment ;-)[/edit]
best regards,
robert