sreadahead: adding readahead system call into bionic libc

Add bionic libc to support readahead system call.
This is needed to enable sreadahead to work.

Change-Id: I3856e1a3833db82e6cf42fd34af7631bd40cc723
Author: Winson Yung <winson.w.yung@intel.com>
Signed-off-by: Bruce Beare <bruce.j.beare@intel.com>
diff --git a/libc/arch-sh/syscalls/readahead.S b/libc/arch-sh/syscalls/readahead.S
new file mode 100644
index 0000000..df64b5f
--- /dev/null
+++ b/libc/arch-sh/syscalls/readahead.S
@@ -0,0 +1,32 @@
+/* autogenerated by gensyscalls.py */
+#include <sys/linux-syscalls.h>
+
+    .text
+    .type readahead, @function
+    .globl readahead
+    .align 4
+
+readahead:
+
+    /* invoke trap */
+    mov.l   0f, r3  /* trap num */
+    trapa   #(4 + 0x10)
+
+    /* check return value */
+    cmp/pz  r0
+    bt      __NR_readahead_end
+
+    /* keep error number */
+    sts.l   pr, @-r15
+    mov.l   1f, r1
+    jsr     @r1
+    mov     r0, r4
+    lds.l   @r15+, pr
+
+__NR_readahead_end:
+    rts
+    nop
+
+    .align  2
+0:  .long   __NR_readahead
+1:  .long   __set_syscall_errno