nir: Add missing dependency on nir_opcodes.py

Commit 38800b38 changed nir_opcodes.py, but that doesn't seem to have
triggered nir_opt_algebraic.py.  The change in 75ef5991 depends on
opt_algebraic lowering 16-bit versions of slt, but if opt_algebraic is
not rebuilt, this may not happen.  This resulted in some people seeing
assertion failures in, for example,
dEQP-VK.spirv_assembly.instruction.compute.float16.arithmetic_3.step,
due to the backend seeing nir_op_slt that it didn't know how to handle.

v2: Add nir_opcodes.py to nir_algebraic_py so that all the per-driver
algebraic passes pick up the dependency too.  Rename it to
nir_algebraic_depends.  Suggested by Emma.

Closes: #6047
Fixes: d1992255bb ("meson: Add build Intel "anv" vulkan driver")
Reviewed-by: Emma Anholt <emma@anholt.net>
Acked-by: Dave Airlie <airlied@redhat.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/15050>

src/compiler/nir/meson.build

@@ -20,6 +20,8 @@
 
 nir_depends = files('nir_opcodes.py', 'nir_intrinsics.py')
 
+nir_algebraic_depends = files('nir_opcodes.py', 'nir_algebraic.py')
+
 nir_builder_opcodes_h = custom_target(
   'nir_builder_opcodes.h',
   input : 'nir_builder_opcodes_h.py',
@@ -62,7 +64,7 @@ nir_opt_algebraic_c = custom_target(
   output : 'nir_opt_algebraic.c',
   command : [prog_python, '@INPUT@'],
   capture : true,
-  depend_files : files('nir_algebraic.py'),
+  depend_files : nir_algebraic_depends,
 )
 
 nir_intrinsics_h = custom_target(
@@ -372,8 +374,6 @@ idep_nir = declare_dependency(
   link_with : _libnir,
 )
 
-nir_algebraic_py = files('nir_algebraic.py')
-
 if with_tests
   test(
     'nir_tests',