Linux: link with --as-needed to eliminate direct dependencies on 15 shared li...

plugin/plugin.gyp

Index: plugin/plugin.gyp
===================================================================
--- plugin/plugin.gyp	(revision 41891)
+++ plugin/plugin.gyp	(working copy)
@@ -232,7 +232,27 @@
             'ldflags': [
               '-Wl,-znodelete',
               '-Wl,--gc-sections',
+              '<!@(pkg-config --libs-only-L xt)',
+              # The Cg libs use three other libraries without linking to them,
+              # which breaks --as-needed, so we have to specify them here before
+              # the --as-needed flag.
+              '-lGL',       # Used by libCgGL
+              '-lpthread',  # Used by libCg
+              '-lm',        # Used by libCg
+              # GYP dumps all static and shared libraries into one archive group
+              # on the command line in arbitrary order, which breaks
+              # --as-needed, so we have to specify the out-of-order ones before
+              # the --as-needed flag.
+              '-lCgGL',
+              '-lGLEW',
+              '-lrt',
+              # Directs the linker to only generate dependencies on libraries
+              # that we actually use. Must come last.
+              '-Wl,--as-needed',
             ],
+            'libraries': [
+              '<!@(pkg-config --libs-only-l xt)',
+            ],
             'conditions' : [
               ['plugin_rpath != ""',
                 {
@@ -251,12 +271,6 @@
             ],
           },
         ],
-        ['OS == "linux"',
-          {
-            'sources': [
-            ],
-          },
-        ],
         ['OS == "win"',
           {
             'dependencies': [