[PATCH] Support __FLT_EVAL_METHOD__ == 16 in math.h

  - GCC will set __FLT_EVAL_METHOD__ to 16 if __fp16 supported, e.g.
    cortex-a55/aarch64.
    - $ aarch64-unknown-elf-gcc -v 2>&1 |grep version
      gcc version 9.2.0 (GCC)
    - $ aarch64-unknown-elf-gcc  -E -dM -mcpu=cortex-a55 - < /dev/null  |grep FLT_EVAL_METHOD
      #define __FLT_EVAL_METHOD__ 16
      #define __FLT_EVAL_METHOD_TS_18661_3__ 16
      #define __FLT_EVAL_METHOD_C99__ 16
  - The behavior of __FLT_EVAL_METHOD__ == 16 is same as
    __FLT_EVAL_METHOD__ == 0 except for float16_t, but newlib didn't
    support float16_t.
---
 newlib/libc/include/math.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/newlib/libc/include/math.h b/newlib/libc/include/math.h
index 1efc5b92c..412ae318a 100644
--- a/newlib/libc/include/math.h
+++ b/newlib/libc/include/math.h
@@ -146,7 +146,7 @@ extern int isnan (double);
   #define __TMP_FLT_EVAL_METHOD
 #endif /* FLT_EVAL_METHOD */
 #if defined FLT_EVAL_METHOD
-  #if FLT_EVAL_METHOD == 0
+  #if (FLT_EVAL_METHOD == 0) || (FLT_EVAL_METHOD == 16)
     typedef float  float_t;
     typedef double double_t;
    #elif FLT_EVAL_METHOD == 1
-- 
2.17.1