(GC_SETJMP_WORKS): Define.

src/s/freebsd.h

@@ -167,3 +167,9 @@
    be seen again in a later read(2), without the CRs.  */
 
 #define BROKEN_PTY_READ_AFTER_EAGAIN 1
+
+/* Tell that garbage collector that setjmp is known to save all
+   registers relevant for conservative garbage collection in the
+   jmp_buf.  */
+
+#define GC_SETJMP_WORKS 1

src/s/msdos.h

@@ -269,3 +269,9 @@ You lose; /* Emacs for DOS must be compiled with DJGPP */
 /* We need a little extra space, see ../../lisp/loadup.el */
 #define SYSTEM_PURESIZE_EXTRA 60000
 #endif
+
+/* Tell that garbage collector that setjmp is known to save all
+   registers relevant for conservative garbage collection in the
+   jmp_buf.  */
+
+#define GC_SETJMP_WORKS 1