Fix an issue that math library header files are not exported by make export.
Create symbolic links of libmcs, newlib and openlibm header to nuttx/include.
When we are using newlib as libm, we can consider newlib-esp32 for esp32
hardware. An it contains some optimization for esp32 hardware.
Besides, two small issues has been fixed.
1. add the tar ball to .gitignore
2. Fix the some build warnings
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>
