[build] Move she-bang to line 1

so that invoking the script as an executable works
from a Python subprocess.Popen.

https: //stackoverflow.com/questions/27606653/oserror-errno-8-exec-format-error

This blocks fxr/834279 (switching to Python output leak scanner).

Fixes errors like:
https://ci.chromium.org/ui/p/fuchsia/builders/try/core.arm64-release/b8784067928575574737/overview

Change-Id: I8dda2f2050801af400a7a761be98f3dfea14bf7f
Reviewed-on: https://fuchsia-review.googlesource.com/c/third_party/github.com/intel/libva/+/833962
Reviewed-by: John Bauman <jbauman@google.com>
diff --git a/fuchsia/gen_version.sh b/fuchsia/gen_version.sh
index c9f0a5c..b266cc2 100755
--- a/fuchsia/gen_version.sh
+++ b/fuchsia/gen_version.sh
@@ -1,3 +1,4 @@
+#!/bin/sh
 # Copyright (c) 2022 Google Inc. All Rights Reserved.
 #
 # Permission is hereby granted, free of charge, to any person obtaining a
@@ -20,10 +21,8 @@
 # TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
-#!/bin/sh
-
 libva_topdir="$1"
 version_h_in="$2"
 version_h_out="$3"
 
-sh $libva_topdir/build/gen_version.sh $libva_topdir $version_h_in > $version_h_out
+sh "$libva_topdir"/build/gen_version.sh "$libva_topdir" "$version_h_in" > "$version_h_out"