util: Add cpuinfo-i386.c

Add cpuinfo.h for i386 and x86_64, and the initialization
for that in util/.  Populate that with a slightly altered
copy of the tcg host probing code.  Other uses of cpuid.h
will be adjusted one patch at a time.

Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

host/include/i386/host/cpuinfo.h

@@ -0,0 +1,38 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ * Host specific cpu indentification for x86.
+ */
+
+#ifndef HOST_CPUINFO_H
+#define HOST_CPUINFO_H
+
+/* Digested version of <cpuid.h> */
+
+#define CPUINFO_ALWAYS          (1u << 0)  /* so cpuinfo is nonzero */
+#define CPUINFO_CMOV            (1u << 1)
+#define CPUINFO_MOVBE           (1u << 2)
+#define CPUINFO_LZCNT           (1u << 3)
+#define CPUINFO_POPCNT          (1u << 4)
+#define CPUINFO_BMI1            (1u << 5)
+#define CPUINFO_BMI2            (1u << 6)
+#define CPUINFO_SSE2            (1u << 7)
+#define CPUINFO_SSE4            (1u << 8)
+#define CPUINFO_AVX1            (1u << 9)
+#define CPUINFO_AVX2            (1u << 10)
+#define CPUINFO_AVX512F         (1u << 11)
+#define CPUINFO_AVX512VL        (1u << 12)
+#define CPUINFO_AVX512BW        (1u << 13)
+#define CPUINFO_AVX512DQ        (1u << 14)
+#define CPUINFO_AVX512VBMI2     (1u << 15)
+#define CPUINFO_ATOMIC_VMOVDQA  (1u << 16)
+
+/* Initialized with a constructor. */
+extern unsigned cpuinfo;
+
+/*
+ * We cannot rely on constructor ordering, so other constructors must
+ * use the function interface rather than the variable above.
+ */
+unsigned cpuinfo_init(void);
+
+#endif /* HOST_CPUINFO_H */

host/include/x86_64/host/cpuinfo.h

@@ -0,0 +1 @@
+#include "host/include/i386/host/cpuinfo.h"