build: fixes for mingw-w64

R=rsc
CC=golang-dev
https://golang.org/cl/4742042

include/libc.h

@@ -292,16 +292,20 @@ extern	char*	getgoroot(void);
 extern	char*	getgoversion(void);
 
 #ifdef _WIN32
+
+#ifndef _WIN64
 struct timespec {
 	int tv_sec;
 	long tv_nsec;
 };
+#define execv(prog, argv) execv(prog, (const char* const*)(argv))
+#define execvp(prog, argv) execvp(prog, (const char**)(argv))
+#endif
+
 extern int nanosleep(const struct timespec *rqtp, struct timespec *rmtp);
 extern int fork(void);
 extern int pread(int fd, void *buf, int n, int off);
 extern int pwrite(int fd, void *buf, int n, int off);
-#define execv(prog, argv) execv(prog, (const char* const*)(argv))
-#define execvp(prog, argv) execvp(prog, (const char**)(argv))
 #define lseek(fd, n, base) _lseeki64(fd, n, base)
 #define mkdir(path, perm) mkdir(path)
 #define pipe(fd) _pipe(fd, 512, O_BINARY)

src/lib9/fmt/dofmt.c

@@ -369,7 +369,7 @@ __ifmt(Fmt *f)
 	}
 #endif
 	if(f->r == 'p'){
-		u = (ulong)va_arg(f->args, void*);
+		u = (uintptr)va_arg(f->args, void*);
 		f->r = 'x';
 		fl |= FmtUnsigned;
 	}else if(fl & FmtVLong){

src/libmach/5.c

@@ -35,7 +35,7 @@
 #include "ureg_arm.h"
 #include <mach.h>
 
-#define	REGOFF(x)	(ulong) (&((struct Ureg *) 0)->x)
+#define	REGOFF(x)	(uintptr) (&((struct Ureg *) 0)->x)
 
 #define SP		REGOFF(r13)
 #define PC		REGOFF(pc)