mesa3d: use --enable-shared-glapi also for Gallium drivers

Needed since this upstream commit:
http://cgit.freedesktop.org/mesa/mesa/commit/configure.ac?h=10.2&id=0432aa064bf5d4d0ad8fc3c4d648b8feb238ddfa



Remove --disable-shared-glapi from the non-DRI-block, this
would break with enabled Gallium drivers.

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>