Don't build alsa.omap3.so with read-only relocations

This causes the world to explode when loading this module for unknown
reasons.
Update prebuilt libaudio.so and alsa.omap3.so

The new modules are built from inside a CM 10 source tree using the CM
10 toolchain and build system.
Add instructions for building audio HAL components from source
Add libasound.so and conf files to prebuilts

These don't really belong with the vendor blobs -- they're built from
source (and in fact, the copies being committed are built directly from
a CM 10 source tree -- they're prebuilt for now to avoid having to
re-add external/alsa-lib to the CyanogenMod project).
proprietary-files.txt: remove libasound.so and other audio cruft

This stuff is either unnecessary or now residing in device/bn/encore.