Add a declaration for __cpuid for the IntelLLVM compiler.
__cpuid is declared in intrin.h, but is "excluded" on non-Windows
platforms.
We add this declaration to compensate.
Fixes #1358
diff --git a/absl/random/internal/randen_detect.cc b/absl/random/internal/randen_detect.cc
index 6dababa..0ad23cb 100644
--- a/absl/random/internal/randen_detect.cc
+++ b/absl/random/internal/randen_detect.cc
@@ -45,6 +45,10 @@
#if defined(ABSL_INTERNAL_USE_X86_CPUID)
#if defined(_WIN32) || defined(_WIN64)
#include <intrin.h> // NOLINT(build/include_order)
+#elif ABSL_HAVE_BUILTIN(__cpuid)
+// MSVC-equivalent __cpuid intrinsic declaration for clang-like compilers
+// for non-Windows build environments.
+void __cpuid(int[4], int);
#else
// MSVC-equivalent __cpuid intrinsic function.
static void __cpuid(int cpu_info[4], int info_type) {
