win64: adjust for two args with setjmp(buf,ctx)

win32/include/_mingw.h

@@ -57,6 +57,8 @@ typedef unsigned __int64 uintptr_t;
 #define __stdcall
 #define _AMD64_ 1
 #define __x86_64 1
+#define USE_MINGW_SETJMP_TWO_ARGS
+#define mingw_getsp tinyc_getsp
 #else
 typedef __int32 intptr_t;
 typedef unsigned __int32 uintptr_t;

win32/lib/chkstk.S

@@ -56,6 +56,14 @@ P0:
     mov     (%rax),%rcx     /* restore ecx */
     jmp     *8(%rax)
 
+/* ---------------------------------------------- */
+/* avoid msvcrt unwind stuff for setjmp/longjmp */
+
+.globl tinyc_getsp
+tinyc_getsp:
+    xor %rax,%rax
+    ret
+
 /* ---------------------------------------------- */
 #endif
 /* ---------------------------------------------- */