Fixed the x86_64 setjmp implementation.

* typedef for jmp_buf was using int where it should be long.
* setjmp was clearing the buffer pointer rather than the signal mask before
  calling sigsetjmp.
* KDL now works without crashing on x86_64.

headers/posix/arch/x86_64/arch_setjmp.h

@@ -6,6 +6,6 @@
 #define _ARCH_SETJMP_H_
 
 
-typedef int __jmp_buf[8];
+typedef unsigned long __jmp_buf[8];
 
 #endif	/* _ARCH_SETJMP_H_ */

src/system/libroot/posix/arch/x86_64/sigsetjmp.S

@@ -31,7 +31,7 @@ FUNCTION_END(setjmp)
 /* int setjmp(jmp_buf buffer) */
 FUNCTION(setjmp):
 	// Jump to sigsetjmp with a zero saveMask.
-	xorl	%edi, %edi
+	xorl	%esi, %esi
 	jmp		sigsetjmp
 FUNCTION_END(setjmp)