missing.h: add missing definitions for __O_TMPFILE

Currently, a missing __O_TMPFILE was only defined for i386 and x86_64,
leaving any other architectures with an "old" toolchain fail miserably
at build time:
    src/import/export-raw.c: In function 'reflink_snapshot':
    src/import/export-raw.c:271:26: error: 'O_TMPFILE' undeclared (first use in this function)
             new_fd = open(d, O_TMPFILE|O_CLOEXEC|O_NOCTTY|O_RDWR, 0600);
                              ^

__O_TMPFILE (and O_TMPFILE) are available since glibc 2.19. However, a
lot of existing toolchains are still using glibc-2.18, and some even
before that, and it is not really possible to update those toolchains.

Instead of defining it only for i386 and x86_64, define __O_TMPFILE
with the specific values for those archs where it is different from the
generic value. Use the values as found in the Linux kernel (v4.8-rc3,
current as of time of commit).

---
Note: tested on ARM (build+run), with glibc-2.18 and linux headers 3.12.
Untested on other archs, though (I have no board to test this).

Changes v1 -> v2:
  - add a comment specifying some are hexa, others are octal.

1 files changed, 13 insertions, 4 deletions

diff --git a/src/basic/missing.h b/src/basic/missing.h
index f8e096605e..13ff51cd35 100644
--- a/src/basic/missing.h
+++ b/src/basic/missing.h
@@ -537,12 +537,21 @@ struct btrfs_ioctl_quota_ctl_args {
 #  define DRM_IOCTL_DROP_MASTER _IO('d', 0x1f)
 #endif
 
-#if defined(__i386__) || defined(__x86_64__)
-
-/* The precise definition of __O_TMPFILE is arch specific, so let's
- * just define this on x86 where we know the value. */
+/* The precise definition of __O_TMPFILE is arch specific; use the
+ * values defined by the kernel (note: some are hexa, some are octal,
+ * duplicated as-is from the kernel definitions):
+ * - alpha, parisc, sparc: each has a specific value;
+ * - others: they use the "generic" value.
+ */
 
 #ifndef __O_TMPFILE
+#if defined(__alpha__)
+#define __O_TMPFILE     0100000000
+#elif defined(__parisc__) || defined(__hppa__)
+#define __O_TMPFILE     0400000000
+#elif defined(__sparc__) || defined(__sparc64__)
+#define __O_TMPFILE     0x2000000
+#else
 #define __O_TMPFILE     020000000
 #endif