Use --as-needed for mips64el

This is required to avoid linking unnecessary system libraries which may
conflict with the ones used in Chromium. As side effect we have to turn
off official build for mips64el.

brightray/brightray.gypi

@@ -277,14 +277,10 @@
               # Specifically tell the linker to perform optimizations.
               # See http://lwn.net/Articles/192624/ .
               '-Wl,-O1',
+              '-Wl,--as-needed',
               '-Wl,--gc-sections',
             ],
           }],  # OS=="linux"
-          ['OS=="linux" and target_arch!="mips64el"', {
-            'ldflags': [
-              '-Wl,--as-needed',
-            ],
-          }],
           ['OS=="linux" and target_arch in ["ia32", "x64", "arm64"]', {
             'cflags': [
               '-flto',