[compiler-rt] Fix addtf3_test.c being skipped due to misplaced include

The test `addtf3_test.c` is currently guarded by `#if defined(CRT_HAS_IEEE_TF)`,
a macro that is declared in `int_lib.h`. However, `int_lib.h` is included *after*
the preprocessor check, which results in the macro not being defined in time
and causes the test to always be skipped.

This patch moves the includes of `fp_test.h` and `int_lib.h` to the top of the
file so that `CRT_HAS_IEEE_TF` is defined before it is checked.

Author: Kostiantyn Lazukin

compiler-rt/test/builtins/Unit/addtf3_test.c

@@ -4,14 +4,14 @@
 #include <fenv.h>
 #include <stdio.h>
 
+#include "fp_test.h"
+#include "int_lib.h"
+
 // The testcase currently assumes IEEE TF format, once that has been
 // fixed the defined(CRT_HAS_IEEE_TF) guard can be removed to enable it for
 // IBM 128 floats as well.
 #if defined(CRT_HAS_IEEE_TF)
 
-#  include "fp_test.h"
-#  include "int_lib.h"
-
 // Returns: a + b
 COMPILER_RT_ABI tf_float __addtf3(tf_float a, tf_float b);