r300g: Use union for rc_print_inline_float

Fixes a warning in GCC 9+ that's been bugging me for a very long time when building Mesa.

Additionally avoids pointer type punning.

Signed-off-by: Joshua Ashton <joshua@froggi.es>

src/gallium/drivers/r300/compiler/radeon_program_print.c

@@ -114,14 +114,17 @@ static void rc_print_inline_float(FILE * f, int index)
 	int r300_exponent = (index >> 3) & 0xf;
 	unsigned r300_mantissa = index & 0x7;
 	unsigned float_exponent;
-	unsigned real_float;
-	float * print_float = (float*) &real_float;
+	union
+	{
+		unsigned u;
+	 	float f;
+	} raw_float;
 
 	r300_exponent -= 7;
 	float_exponent = r300_exponent + 127;
-	real_float = (r300_mantissa << 20) | (float_exponent << 23);
+	raw_float.u = (r300_mantissa << 20) | (float_exponent << 23);
 
-	fprintf(f, "%f (0x%x)", *print_float, index);
+	fprintf(f, "%f (0x%x)", raw_float.f, index);
 
 }