microblaze port

based on initial work by rdp, with heavy modifications. some features
including threads are untested because qemu app-level emulation seems
to be broken and I do not have a proper system image for testing.

arch/microblaze/syscall_arch.h

@@ -0,0 +1,41 @@
+#define __SYSCALL_LL_E(x) \
+((union { long long ll; long l[2]; }){ .ll = x }).l[0], \
+((union { long long ll; long l[2]; }){ .ll = x }).l[1]
+#define __SYSCALL_LL_O(x) 0, __SYSCALL_LL_E((x))
+
+#define __SYSCALL_SSLEN 8
+
+static inline long __syscall0(long n)
+{
+	return (__syscall)(n);
+}
+
+static inline long __syscall1(long n, long a)
+{
+	return (__syscall)(n, a);
+}
+
+static inline long __syscall2(long n, long a, long b)
+{
+	return (__syscall)(n, a, b);
+}
+
+static inline long __syscall3(long n, long a, long b, long c)
+{
+	return (__syscall)(n, a, b, c);
+}
+
+static inline long __syscall4(long n, long a, long b, long c, long d)
+{
+	return (__syscall)(n, a, b, c, d);
+}
+
+static inline long __syscall5(long n, long a, long b, long c, long d, long e)
+{
+	return (__syscall)(n, a, b, c, d, e);
+}
+
+static inline long __syscall6(long n, long a, long b, long c, long d, long e, long f)
+{
+	return (__syscall)(n, a, b, c, d, e, f);
+}