Expose full LLVM sources

We need the `cmake` config and the `.a` files for IWYU

CMK-22333

Change-Id: I0e0a213450fa6f9bf222608eb4f49b0786af5905

Author: Synss

MODULE.bazel

@@ -75,6 +75,11 @@ git_override(
     remote = "https://github.com/hedronvision/bazel-compile-commands-extractor.git",
 )
 
+single_version_override(
+    module_name = "toolchains_llvm",
+    patch_strip = 1,
+    patches = ["//bazel/patches:toolchains_llvm-expose_full_archive.patch"],
+)
 single_version_override(
     module_name = "protobuf",
     patch_strip = 1,

bazel/patches/toolchains_llvm-expose_full_archive.patch

@@ -0,0 +1,16 @@
+diff --git a/toolchain/BUILD.llvm_repo b/toolchain/BUILD.llvm_repo
+index f2bbc76..963c772 100644
+--- a/toolchain/BUILD.llvm_repo
++++ b/toolchain/BUILD.llvm_repo
+@@ -25,6 +25,11 @@ exports_files(glob(
+     allow_empty = True,
+ ))
+ 
++filegroup(
++    name = "srcs",
++    srcs = glob(["**"]),
++)
++
+ ## LLVM toolchain files
+ 
+ filegroup(