Move code-generation scripts to scripts/codegen

Now that we have a scripts/* directory, let's put the scripts we use
for generating C there.

scripts/codegen/gen_linux_syscalls.pl

@@ -0,0 +1,37 @@
+#!/usr/bin/perl -w
+
+use strict;
+my %syscalls = ();
+
+while (<>) {
+    if (/^#define (__NR_\w+) /) {
+	$syscalls{$1} = 1;
+    }
+}
+
+print <<EOL;
+/* Automatically generated with
+        gen_linux_syscalls.pl /usr/include/asm/unistd*.h
+   Do not edit.
+ */
+static const struct {
+  int syscall_num; const char *syscall_name;
+} SYSCALLS_BY_NUMBER[] = {
+EOL
+
+for my $k (sort keys %syscalls) {
+    my $name = $k;
+    $name =~ s/^__NR_//;
+    print <<EOL;
+#ifdef $k
+  { $k, "$name" },
+#endif
+EOL
+
+}
+
+print <<EOL
+  {0, NULL}
+};
+
+EOL