pipe-loader: link against libloader regardless of libdrm presence

Whether or not the loader has libdrm support is up-to it. Anyone using
the loader should just include it whenever they depend on it.

Cc: mesa-stable@lists.freedesktop.org
Fixes: 0f39f9cb7a "pipe-loader: add a dummy 'static' pipe-loader"
Reported-by: Jon TURNEY <jon.turney@dronecode.org.uk>
Tested-by: Jon TURNEY <jon.turney@dronecode.org.uk>
Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>

src/gallium/auxiliary/pipe-loader/Makefile.am

 libpipe_loader_dynamic_la_SOURCES += \
 	$(DRM_SOURCES)
 
+endif
+
 libpipe_loader_static_la_LIBADD = \
 	$(top_builddir)/src/loader/libloader.la
 
 libpipe_loader_dynamic_la_LIBADD = \
 	$(top_builddir)/src/loader/libloader.la
 
-endif
-
 EXTRA_DIST = SConscript