Subject: [PATCH] abseil: include BMI2 intrinsics through the public header

GCC and Clang reject direct inclusion of bmi2intrin.h. Include immintrin.h
instead so that the compiler supplies the required intrinsic setup when
BMI2 is enabled, including builds targeting x86-64-v3.

This patch is shared by the vendored Abseil copies in Electron, rusty_v8
(Deno), and Signal's WebRTC build.

--- a/third_party/abseil-cpp/absl/container/internal/raw_hash_set.h
+++ b/third_party/abseil-cpp/absl/container/internal/raw_hash_set.h
@@ -226,7 +226,7 @@
 #endif
 
 #ifdef __BMI2__
-#include <bmi2intrin.h>
+#include <immintrin.h>
 #endif  // __BMI2__
 
 namespace absl {