softfloat: Fix compilation failures with USE_SOFTFLOAT_STRUCT_TYPES

Make softfloat compile with USE_SOFTFLOAT_STRUCT_TYPES defined, by
adding and using new macros const_float16(), const_float32() and
const_float64() so you can use array initializers in an array of
float16/float32/float64 whether the types are bare or wrapped in the
structs.

[aurelien@aurel32.net: do the same for float16]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 3abd170..30b07e9 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -2199,21 +2199,21 @@
 
 static const float64 float32_exp2_coefficients[15] =
 {
-    make_float64( 0x3ff0000000000000ll ), /*  1 */
-    make_float64( 0x3fe0000000000000ll ), /*  2 */
-    make_float64( 0x3fc5555555555555ll ), /*  3 */
-    make_float64( 0x3fa5555555555555ll ), /*  4 */
-    make_float64( 0x3f81111111111111ll ), /*  5 */
-    make_float64( 0x3f56c16c16c16c17ll ), /*  6 */
-    make_float64( 0x3f2a01a01a01a01all ), /*  7 */
-    make_float64( 0x3efa01a01a01a01all ), /*  8 */
-    make_float64( 0x3ec71de3a556c734ll ), /*  9 */
-    make_float64( 0x3e927e4fb7789f5cll ), /* 10 */
-    make_float64( 0x3e5ae64567f544e4ll ), /* 11 */
-    make_float64( 0x3e21eed8eff8d898ll ), /* 12 */
-    make_float64( 0x3de6124613a86d09ll ), /* 13 */
-    make_float64( 0x3da93974a8c07c9dll ), /* 14 */
-    make_float64( 0x3d6ae7f3e733b81fll ), /* 15 */
+    const_float64( 0x3ff0000000000000ll ), /*  1 */
+    const_float64( 0x3fe0000000000000ll ), /*  2 */
+    const_float64( 0x3fc5555555555555ll ), /*  3 */
+    const_float64( 0x3fa5555555555555ll ), /*  4 */
+    const_float64( 0x3f81111111111111ll ), /*  5 */
+    const_float64( 0x3f56c16c16c16c17ll ), /*  6 */
+    const_float64( 0x3f2a01a01a01a01all ), /*  7 */
+    const_float64( 0x3efa01a01a01a01all ), /*  8 */
+    const_float64( 0x3ec71de3a556c734ll ), /*  9 */
+    const_float64( 0x3e927e4fb7789f5cll ), /* 10 */
+    const_float64( 0x3e5ae64567f544e4ll ), /* 11 */
+    const_float64( 0x3e21eed8eff8d898ll ), /* 12 */
+    const_float64( 0x3de6124613a86d09ll ), /* 13 */
+    const_float64( 0x3da93974a8c07c9dll ), /* 14 */
+    const_float64( 0x3d6ae7f3e733b81fll ), /* 15 */
 };
 
 float32 float32_exp2( float32 a STATUS_PARAM )