linux: Make native modules work.

atom.gyp

@@ -399,11 +399,13 @@
         }],  # OS=="mac"
         ['OS=="linux"', {
           'link_settings': {
+            'ldflags': [
               # Make binary search for libraries under current directory, so we
               # don't have to manually set $LD_LIBRARY_PATH:
               # http://serverfault.com/questions/279068/cant-find-so-in-the-same-directory-as-the-executable
-            'ldflags': [
               '-rpath \$$ORIGIN',
+              # Make native module dynamic loading work.
+              '-rdynamic',
             ],
           },
         }],  # OS=="linux"