radeon: Build and use libradeon the right way.

Better build system integration for:
http://cgit.freedesktop.org/mesa/mesa/commit/?id=91a160b
http://cgit.freedesktop.org/mesa/mesa/commit/?id=5b2855b

The EGL runtime issue should be fixed now.
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=64810
gallium/targets: Make use of prebuilt libdricommon.la.
Drop support for --enable-static / --disable-shared.
gallium/auxiliary: Build libgallium shared.
Drop last parts of compatibility for the old Mesa build system.
mapi: Build libglapi always shared.
mesa: Build libmesa shared.
Install all internal shared libs to $(libdir)/mesa-$VERSION.
Also do it for egl_gallium.so, pipe_*.so and gbm_gallium_drm.
Makefile.am: s:-no-undefined:-Wl,--no-undefined to make it work.
gallium/drivers: Build libs -shared.
vdpau,xvmc: Add install-data-hooks to remove unneccessary symlinks.

libvdpau_*.so.1 and libXvMC*.so libs are dlopened by wrappers.
So only those libs should be installed.
glx: Get rid of libglx.la.
gbm: Get rid of libgbm_dri.la.
i915: Conditionally build an i915g driver instead of two i915 drivers.
freedreno: Make print_sequence a macro to fix clang.
freedreno: One Makefile.am with a Makefile.sources is enough.
clover: Force gcc and g++ to fix clang builds.
gallium/auxiliary/draw/draw_decompose_tmp.h: Fix clang warnings.
More scan-build fixes.