typed arrays: fix build on sunos

src/v8_typed_array_bswap.h

@@ -131,6 +131,8 @@ inline uint8_t SwapBytes(uint8_t x) { return x; }
 template <>
 inline int8_t SwapBytes(int8_t x) { return x; }
 template <>
+inline signed char SwapBytes(signed char x) { return x; }
+template <>
 inline uint16_t SwapBytes(uint16_t x) { return V8_TYPED_ARRAY_BSWAP16(x); }
 template <>
 inline int16_t SwapBytes(int16_t x) { return V8_TYPED_ARRAY_BSWAP16(x); }