Add ignore_libs in the libva pkg_config

libva is dlopened regardless

Change-Id: Ice577ef78ea15ab7041db4b386eb91237d46a3d3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2442189Reviewed-by: Bruce Dawson <brucedawson@chromium.org>
Reviewed-by: Dale Curtis <dalecurtis@chromium.org>
Reviewed-by: Andres Calderon Jaramillo <andrescj@chromium.org>
Commit-Queue: Ted Meyer <tmathmeyer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#816663}

build/config/linux/libva/BUILD.gn

@@ -8,6 +8,10 @@ assert(is_linux || is_chromeos, "This file should only be referenced on Linux")
 
 pkg_config("libva") {
   packages = [ "libva" ]
+
   # Do not use exec_script to check the version here. It is done with a
   # static_assert instead.
+
+  # vaapi decoders use dlopen pre-sandbox anyway to improve startup times.
+  ignore_libs = true
 }