fix remaining direct use of stat syscalls outside fstatat.c

because struct stat is no longer assumed to correspond to the
structure used by the stat-family syscalls, it's not valid to make any
of these syscalls directly using a buffer of type struct stat.

commit 9493892021 moved all logic around
this change for stat-family functions into fstatat.c, making the
others wrappers for it. but a few other direct uses of the syscall
were overlooked. the ones in tmpnam/tempnam are harmless since the
syscalls are just used to test for file existence. however, the uses
in fchmodat and __map_file depend on getting accurate file properties,
and these functions may actually have been broken one or more mips
variants due to removal of conversion hacks from syscall_arch.h.

as a low-risk fix, simply use struct kstat in place of struct stat in
the affected places.

src/stat/fchmodat.c

@@ -2,6 +2,7 @@
 #include <fcntl.h>
 #include <errno.h>
 #include "syscall.h"
+#include "kstat.h"
 
 int fchmodat(int fd, const char *path, mode_t mode, int flag)
 {
@@ -10,7 +11,7 @@ int fchmodat(int fd, const char *path, mode_t mode, int flag)
 	if (flag != AT_SYMLINK_NOFOLLOW)
 		return __syscall_ret(-EINVAL);
 
-	struct stat st;
+	struct kstat st;
 	int ret, fd2;
 	char proc[15+3*sizeof(int)];
 

src/stdio/tempnam.c

@@ -6,6 +6,7 @@
 #include <string.h>
 #include <stdlib.h>
 #include "syscall.h"
+#include "kstat.h"
 
 #define MAXTRIES 100
 
@@ -37,10 +38,10 @@ char *tempnam(const char *dir, const char *pfx)
 	for (try=0; try<MAXTRIES; try++) {
 		__randname(s+l-6);
 #ifdef SYS_lstat
-		r = __syscall(SYS_lstat, s, &(struct stat){0});
+		r = __syscall(SYS_lstat, s, &(struct kstat){0});
 #else
 		r = __syscall(SYS_fstatat, AT_FDCWD, s,
-			&(struct stat){0}, AT_SYMLINK_NOFOLLOW);
+			&(struct kstat){0}, AT_SYMLINK_NOFOLLOW);
 #endif
 		if (r == -ENOENT) return strdup(s);
 	}

src/stdio/tmpnam.c

@@ -5,6 +5,7 @@
 #include <string.h>
 #include <stdlib.h>
 #include "syscall.h"
+#include "kstat.h"
 
 #define MAXTRIES 100
 
@@ -17,10 +18,10 @@ char *tmpnam(char *buf)
 	for (try=0; try<MAXTRIES; try++) {
 		__randname(s+12);
 #ifdef SYS_lstat
-		r = __syscall(SYS_lstat, s, &(struct stat){0});
+		r = __syscall(SYS_lstat, s, &(struct kstat){0});
 #else
 		r = __syscall(SYS_fstatat, AT_FDCWD, s,
-			&(struct stat){0}, AT_SYMLINK_NOFOLLOW);
+			&(struct kstat){0}, AT_SYMLINK_NOFOLLOW);
 #endif
 		if (r == -ENOENT) return strcpy(buf ? buf : internal, s);
 	}

src/time/__map_file.c

@@ -2,10 +2,11 @@
 #include <fcntl.h>
 #include <sys/stat.h>
 #include "syscall.h"
+#include "kstat.h"
 
 const char unsigned *__map_file(const char *pathname, size_t *size)
 {
-	struct stat st;
+	struct kstat st;
 	const unsigned char *map = MAP_FAILED;
 	int fd = sys_open(pathname, O_RDONLY|O_CLOEXEC|O_NONBLOCK);
 	if (fd < 0) return 0;