tcg/ppc: Enable Altivec detection

Now that we have implemented the required tcg operations,
we can enable detection of host vector support.

Tested-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk> (PPC32)
Reviewed-by: Aleksandar Markovic <amarkovic@wavecomp.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

tcg/ppc/tcg-target.inc.c

@@ -3528,6 +3528,10 @@ static void tcg_target_init(TCGContext *s)
     have_isel = have_isa_2_06;
 #endif
 
+    if (hwcap & PPC_FEATURE_HAS_ALTIVEC) {
+        have_altivec = true;
+    }
+
     tcg_target_available_regs[TCG_TYPE_I32] = 0xffffffff;
     tcg_target_available_regs[TCG_TYPE_I64] = 0xffffffff;
     if (have_altivec) {