This patch restores LLVM targets needed for OpenCL, *reverting* this
upstream commit:

  From 80817b6e344258ac9b955f824ebf9019a0fc1610 Mon Sep 17 00:00:00 2001
  From: Jesse Natalie <jenatali@microsoft.com>
  Date: Wed, 18 Nov 2020 18:30:30 -0800
  Subject: [PATCH] meson: Adjust Clover's required LLVM modules

diff --git a/meson.build b/meson.build
index 6d1607c35a3..f828eb80faa 100644
--- b/meson.build
+++ a/meson.build
@@ -1479,10 +1479,9 @@
 endif
 if with_gallium_opencl
   llvm_modules += [
-    'linker', 'coverage', 'instrumentation', 'ipo', 'irreader',
-    'lto', 'option', 'objcarcopts', 'profiledata'
+    'all-targets', 'linker', 'coverage', 'instrumentation', 'ipo', 'irreader',
+    'lto', 'option', 'objcarcopts', 'profiledata',
   ]
-  llvm_optional_modules += ['frontendopenmp']
 endif
 if with_microsoft_clc
   llvm_modules += ['target', 'linker', 'irreader', 'option', 'libdriver']