Disable sysroot for x86 and x64 only

In addition to https://codereview.chromium.org/1526163002
disable sysroot only for x86 and x64.

Keep using sysroot for other archs
due to crosscompiling.

BUG=none
R=fbarchard@chromium.org

Review URL: https://codereview.chromium.org/1536403002 .

libyuv.gyp

@@ -21,7 +21,13 @@
       # Disable use of sysroot for Linux. It's enabled by default in Chromium,
       # but it currently lacks the libudev-dev package.
       # TODO(kjellander): Remove when crbug.com/561584 is fixed.
+      'conditions': [
+         ['target_arch=="ia32" or target_arch=="x64"', {
            'use_sysroot': 0,
+         }, {
+           'use_sysroot%': 1,
+         }],
+       ],
     },
     'use_sysroot%': '<(use_sysroot)',
     'use_system_libjpeg%': 0,