make it possible to disable the use of libpci on linux again

build/linux/system.gyp

 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 {
   'variables': {
     'conditions': [
       ['sysroot!=""', {
         'pkg-config': '<(chroot_cmd) ./pkg-config-wrapper "<(sysroot)" "<(target_arch)" "<(system_libdir)"',
       }, {
         'pkg-config': 'pkg-config',
       }],
     ],
 
+    # If any of the linux_link_FOO below are set to 1, then the corresponding
+    # target will be linked against the FOO library (either dynamically or
+    # statically, depending on the pkg-config files), as opposed to loading the
+    # FOO library dynamically with dlopen.
     'linux_link_libgps%': 0,
     'linux_link_libpci%': 0,
     'linux_link_libspeechd%': 0,
     'linux_link_libbrlapi%': 0,
   },
   'conditions': [
     [ 'chromeos==0 and use_ozone==0', {
       # Hide GTK and related dependencies for Chrome OS and Ozone, so they won't get
       # added back to Chrome OS and Ozone. Don't try to use GTK on Chrome OS and Ozone.
       'targets': [
@@ skipping 1020 matching lines @@
             ],
             'libraries': [
               '<!@(<(pkg-config) --libs-only-l libudev)',
             ],
           },
         }],
       ],
     },
   ],
 }