gallium: Fix autotools build with libxatracker.la.

gallium: Fix autotools build with libxatracker.la.

  CXXLD    libxatracker.la
/usr/bin/ld: ../../../../src/gallium/auxiliary/.libs/libgallium.a(tgsi_to_nir.o): in function `ttn_finalize_nir':
src/gallium/auxiliary/nir/tgsi_to_nir.c:2111: undefined reference to `gl_nir_lower_samplers_as_deref'
/usr/bin/ld: src/gallium/auxiliary/nir/tgsi_to_nir.c:2113: undefined reference to `gl_nir_lower_samplers'

Fixes: 9a834447d652 ("tgsi_to_nir: Produce optimized NIR for a given pipe_screen.")
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=109929
Signed-off-by: Vinson Lee <vlee@freedesktop.org>