util: Introduce fui() and uif() helpers for bit-casting floats/uints.

I wanted to fix up some type-punning warnings and was surprised to see
we didn't have this yet.
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>

tests/util/piglit-util.h

@@ -467,6 +467,26 @@ piglit_alloc_aligned(size_t alignment, size_t size);
 void
 piglit_free_aligned(void *p);
 
+union uif {
+	float f;
+	unsigned int ui;
+};
+
+static inline unsigned int
+fui(float f)
+{
+	union uif bits;
+	bits.f = f;
+	return bits.ui;
+}
+
+static inline float
+uif(unsigned int ui)
+{
+	union uif bits;
+	bits.ui = ui;
+	return bits.f;
+}
 
 #ifdef __cplusplus
 } /* end extern "C" */