ntdll: Add %gs support for FreeBSD.

configure

@@ -5837,6 +5837,7 @@ for ac_header in \
 	machine/cpu.h \
 	machine/limits.h \
 	machine/soundcard.h \
+	machine/sysarch.h \
 	mntent.h \
 	mpg123.h \
 	ncurses.h \

configure.ac

@@ -422,6 +422,7 @@ AC_CHECK_HEADERS(\
 	machine/cpu.h \
 	machine/limits.h \
 	machine/soundcard.h \
+	machine/sysarch.h \
 	mntent.h \
 	mpg123.h \
 	ncurses.h \

dlls/ntdll/signal_x86_64.c

@@ -28,10 +28,15 @@
 #include <stdlib.h>
 #include <stdarg.h>
 #include <stdio.h>
+
 #ifdef HAVE_UNISTD_H
 # include <unistd.h>
 #endif
 
+#ifdef HAVE_MACHINE_SYSARCH_H
+# include <machine/sysarch.h>
+#endif
+
 #ifdef HAVE_SYS_PARAM_H
 # include <sys/param.h>
 #endif
@@ -2288,8 +2293,10 @@ void signal_init_thread( TEB *teb )
 {
     stack_t ss;
 
-#ifdef __linux__
+#if defined __linux__
     arch_prctl( ARCH_SET_GS, teb );
+#elif defined __FreeBSD__
+    amd64_set_gsbase( teb );
 #else
 # error Please define setting %gs for your architecture
 #endif

include/config.h.in

@@ -461,6 +461,9 @@
 /* Define to 1 if you have the <machine/soundcard.h> header file. */
 #undef HAVE_MACHINE_SOUNDCARD_H
 
+/* Define to 1 if you have the <machine/sysarch.h> header file. */
+#undef HAVE_MACHINE_SYSARCH_H
+
 /* Define to 1 if you have the <mach/machine.h> header file. */
 #undef HAVE_MACH_MACHINE_H