Add cfi directives to x86 syscalls.

Modify the syscalls script to generate the cfi directives for x86
syscalls.

Update the x86 syscalls.

Change-Id: Ia1993dc714a7e79f917087fff8200e9a02c52603
diff --git a/libc/arch-x86/syscalls/recvfrom.S b/libc/arch-x86/syscalls/recvfrom.S
index c266e93..df489c8 100644
--- a/libc/arch-x86/syscalls/recvfrom.S
+++ b/libc/arch-x86/syscalls/recvfrom.S
@@ -5,6 +5,9 @@
 ENTRY(recvfrom)
     pushl   %ebx
     pushl   %ecx
+    .cfi_def_cfa_offset 8
+    .cfi_rel_offset ebx, 0
+    .cfi_rel_offset ecx, 4
     mov     $12, %ebx
     mov     %esp, %ecx
     addl    $12, %ecx