Fix error :
nuttx/libs/libm/newlib/include/math.h:89:8: error: ‘_Thread_local’ does not name a type; did you mean ‘thread_local’?
89 | extern _Thread_local int _tls_gamma_signgam;
| ^~~~~~~~~~~~~
| thread_local
In file included from /mnt/nuttx/include/libcxx/math.h:300,
from /mnt/nuttx/include/libcxx/cmath:308,
from /mnt/nuttx/include/libcxx/charconv:79,
from libcxx/src/string.cpp:10:
/mnt/nuttx/libs/libm/newlib/include/math.h:89:8: error: ‘_Thread_local’ does not name a type; did you mean ‘thread_local’?
89 | extern _Thread_local int _tls_gamma_signgam;
Signed-off-by: yanghuatao <yanghuatao@xiaomi.com>
