Use pthread_setaffinity_np() on FreeBSD as well

libs/fiber/src/numa/freebsd/pin_thread.cpp:13:10: fatal error: 'sys/thread.h' file not found
 #include <sys/thread.h>
          ^~~~~~~~~~~~~~

libs/fiber/src/numa/freebsd/pin_thread.cpp:28:35: error: too few arguments to function call, single argument 'id' was not specified
    pin_thread( cpuid, ::thr_self() );
                       ~~~~~~~~~~ ^
/usr/include/sys/thr.h:77:1: note: 'thr_self' declared here
int thr_self(long *id);
^

libs/fiber/src/numa/freebsd/pin_thread.cpp:36:85: error: cannot initialize a parameter of type 'id_t' (aka 'long') with an lvalue of type 'std::thread::native_handle_type' (aka 'pthread *')
    if ( BOOST_UNLIKELY( 0 != ::cpuset_setaffinity( CPU_LEVEL_WHICH, CPU_WHICH_TID, h, sizeof( mask), & mask) ) ) {
                                                                                    ^
./boost/config/compiler/clang.hpp:67:44: note: expanded from macro 'BOOST_UNLIKELY'
 #define BOOST_UNLIKELY(x) __builtin_expect(x, 0)
                                            ^
/usr/include/sys/cpuset.h:156:52: note: passing argument to parameter here
int     cpuset_setaffinity(cpulevel_t, cpuwhich_t, id_t, size_t, const cpuset_t *);
                                                       ^

src/numa/freebsd/pin_thread.cpp

@@ -7,10 +7,8 @@
 #include "boost/fiber/numa/pin_thread.hpp"
 
 extern "C" {
-#include <errno.h>
-#include <sys/param.h>
-#include <sys/cpuset.h>
-#include <sys/thread.h>
+#include <pthread.h>
+#include <pthread_np.h>
 }
 
 #include <system_error>
@@ -25,18 +23,19 @@ namespace numa {
 
 BOOST_FIBERS_DECL
 void pin_thread( std::uint32_t cpuid) {
-    pin_thread( cpuid, ::thr_self() );
+    pin_thread( cpuid, ::pthread_self() );
 }
 
 BOOST_FIBERS_DECL
 void pin_thread( std::uint32_t cpuid, std::thread::native_handle_type h) {
-	cpuset_t mask;
-	CPU_ZERO( & mask);
-	CPU_SET( cpuid, & mask);
-    if ( BOOST_UNLIKELY( 0 != ::cpuset_setaffinity( CPU_LEVEL_WHICH, CPU_WHICH_TID, h, sizeof( mask), & mask) ) ) {
+    cpuset_t set;
+    CPU_ZERO( & set);
+    CPU_SET( cpuid, & set);
+    int err = 0;
+    if ( BOOST_UNLIKELY( 0 != ( err = ::pthread_setaffinity_np( h, sizeof( set), & set) ) ) ) {
         throw std::system_error(
-                std::error_code( errno, std::system_category() ),
-                "::cpuset_setaffinity() failed");
+                std::error_code( err, std::system_category() ),
+                "pthread_setaffinity_np() failed");
     }
 }