crt: tests: remove explicit calls to `__mingw_printf`

Tests `t_float` and `t_speed_powl` directly call `__mingw_printf`; according
to relevant commit messages, it was done to suppress some compiler warnings.

Instead of calling `__mingw_printf` directly, define `__MINGW_USE_ANSI_STDIO`
to non-zero and use mingw-w64's `printf`.

Signed-off-by: Kirill Makurin <maiddaisuki@outlook.com>
Signed-off-by: LIU Hao <lh_mouse@126.com>

mingw-w64-crt/testcases/t_float.c

diff --git a/mingw-w64-crt/testcases/t_float.c b/mingw-w64-crt/testcases/t_float.c
index 59d7f74..fc06599 100644
--- a/mingw-w64-crt/testcases/t_float.c
+++ b/mingw-w64-crt/testcases/t_float.c
@@ -1,3 +1,4 @@
+#define __MINGW_USE_ANSI_STDIO 1
 #include <inttypes.h>
 #include <math.h>
 #include <stdio.h>
@@ -111,7 +112,7 @@
   ARG3_FCT (fma, 2.0, 1.5);
   printf ("%g is%s nan\n", (double) in1, isnan (in1) ? "" :" not");
   printf ("%g is%s inf\n", (double) in1, isinf (in1) ? "" :" not");
-  __mingw_printf ("Ld:%Lg d:%g f:%g\n", ld1, ld2, (double) ld3);
+  printf ("Ld:%Lg d:%g f:%g\n", ld1, ld2, (double) ld3);
 
   return 0;
 }

mingw-w64-crt/testcases/t_speed_powl.c

diff --git a/mingw-w64-crt/testcases/t_speed_powl.c b/mingw-w64-crt/testcases/t_speed_powl.c
index 87a7e94..bd2dfd4 100644
--- a/mingw-w64-crt/testcases/t_speed_powl.c
+++ b/mingw-w64-crt/testcases/t_speed_powl.c
@@ -1,3 +1,4 @@
+#define __MINGW_USE_ANSI_STDIO 1
 #include <math.h>
 #include <stdio.h>
 
@@ -23,7 +24,7 @@
 
   start_ticks = GetTickCount() - start_ticks;
 
-  __mingw_printf ("Loop %d times with result %Lg\n", i, ld);
+  printf ("Loop %d times with result %Lg\n", i, ld);
   printf ("Has %g calculations / ms\n", (double) i / (double) start_ticks);
 
   (void)sum;