This patch replaces s_rint.c in sysdeps/dbl-64 with the one in
sysdeps/dbl-64/wordsize-64 and removes the latter one.
The code is not changed except changes in code style.
Also adjusted the include path in x86_64 file.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Provide macros so that the internal users can, if possible, directly use
the new instructions.
Also fix up the mathinline.h header when compiling with SSE4.1 enabled.
