i386: Add spec-ctrl CPUID bit

Add the feature name and a CPUID_7_0_EDX_SPEC_CTRL macro.
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>
Message-Id: <20180109154519.25634-4-ehabkost@redhat.com>
Signed-off-by: NEduardo Habkost <ehabkost@redhat.com>

target/i386/cpu.c

@@ -459,7 +459,7 @@ static FeatureWordInfo feature_word_info[FEATURE_WORDS] = {
             NULL, NULL, NULL, NULL,
             NULL, NULL, NULL, NULL,
             NULL, NULL, NULL, NULL,
-            NULL, NULL, NULL, NULL,
+            NULL, NULL, "spec-ctrl", NULL,
             NULL, NULL, NULL, NULL,
         },
         .cpuid_eax = 7,

target/i386/cpu.h

@@ -667,6 +667,7 @@ typedef uint32_t FeatureWordArray[FEATURE_WORDS];
 
 #define CPUID_7_0_EDX_AVX512_4VNNIW (1U << 2) /* AVX512 Neural Network Instructions */
 #define CPUID_7_0_EDX_AVX512_4FMAPS (1U << 3) /* AVX512 Multiply Accumulation Single Precision */
+#define CPUID_7_0_EDX_SPEC_CTRL     (1U << 26) /* Speculation Control */
 
 #define CPUID_XSAVE_XSAVEOPT   (1U << 0)
 #define CPUID_XSAVE_XSAVEC     (1U << 1)