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-arm/syscalls/readahead.S b/libc/arch-arm/syscalls/readahead.S
new file mode 100644
index 0000000..6aa8265
--- /dev/null
+++ b/libc/arch-arm/syscalls/readahead.S
@@ -0,0 +1,16 @@
+/* autogenerated by gensyscalls.py */
+#include <machine/asm.h>
+#include <sys/linux-syscalls.h>
+
+ENTRY(readahead)
+    mov     ip, sp
+    .save   {r4, r5, r6, r7}
+    stmfd   sp!, {r4, r5, r6, r7}
+    ldmfd   ip, {r4, r5, r6}
+    ldr     r7, =__NR_readahead
+    swi     #0
+    ldmfd   sp!, {r4, r5, r6, r7}
+    movs    r0, r0
+    bxpl    lr
+    b       __set_syscall_errno
+END(readahead)