configure: add HAVE_GALLIUM_STATIC_TARGETS

Will be used to control the linking mode of pipe-drivers
in gallium targets.

Keep this hardcoded to static, as the pipe-drivers bare
an unstable interface which we do not want to expose to
the normal user.

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
diff --git a/configure.ac b/configure.ac
index 9c0c77d..8f86154 100644
--- a/configure.ac
+++ b/configure.ac
@@ -2057,6 +2057,10 @@
 AM_CONDITIONAL(NEED_GALLIUM_LLVMPIPE_DRIVER, test "x$HAVE_GALLIUM_SOFTPIPE" = xyes \
                                                   && test "x$MESA_LLVM" = x1)
 
+# Enable static gallium targets for now.
+# Do not touch this unless you know what you are doing.
+AM_CONDITIONAL(HAVE_GALLIUM_STATIC_TARGETS, test "xyes" = xyes)
+
 # NOTE: anything using xcb or other client side libs ends up in separate
 #       _CLIENT variables.  The pipe loader is built in two variants,
 #       one that is standalone and does not link any x client libs (for