Merge bitcoin/bitcoin#31308: ci, iwyu: Treat warnings as errors for specific directories

02d2b5a11c ci, iwyu: Treat warnings as errors for specific directories (Hennadii Stepanov)
57a3eac387 refactor: Fix includes in `index` directory (Hennadii Stepanov)
bdb8eadcdc refactor: Fix includes in `crypto` directory (Hennadii Stepanov)
56f2a689a2 ci: Do not patch `leveldb` to workaround UB in "tidy" CI job (Hennadii Stepanov)

Pull request description:

  This PR is the first step towards treating IWYU warnings as errors. At this stage, it applies only to the `crypto` and `index` directories.

ACKs for top commit:
  maflcko:
    re-ACK 02d2b5a11c 💮
  ryanofsky:
    Code review ACK 02d2b5a11c. Just rebased and update tidy patch comment again since last review
  willcl-ark:
    ACK 02d2b5a11c

Tree-SHA512: 1c966e01c47bf3e7d225faa3b819367f757430e2d71e9582fa82d67307aabe3f0d76f69346ee180192e7f5ab194ecc58d2b8ecf178eab26ba3309a6b55bff4b6

contrib/devtools/iwyu/bitcoin.core.imp

@@ -1,3 +1,16 @@
-# Nothing for now.
 [
+  # Compiler intrinsics.
+  # See: https://github.com/include-what-you-use/include-what-you-use/issues/1764.
+  { "include": [ "<emmintrin.h>", "private", "<immintrin.h>", "public" ] },
+  { "include": [ "<smmintrin.h>", "private", "<immintrin.h>", "public" ] },
+  { "include": [ "<tmmintrin.h>", "private", "<immintrin.h>", "public" ] },
+
+  # libc symbols.
+  { "symbol": ["AT_HWCAP", "private", "<sys/auxv.h>", "public"] },
+  { "symbol": ["AT_HWCAP2", "private", "<sys/auxv.h>", "public"] },
+
+  # Fixed in https://github.com/include-what-you-use/include-what-you-use/pull/1706.
+  { "symbol": ["SEEK_CUR", "private", "<cstdio>", "public"] },
+  { "symbol": ["SEEK_END", "private", "<cstdio>", "public"] },
+  { "symbol": ["SEEK_SET", "private", "<cstdio>", "public"] },
 ]