linux/gyp: Find missing symbols at build time, not runtime.

build/common.gypi

Index: build/common.gypi
diff --git a/build/common.gypi b/build/common.gypi
index d1492320f727797ac8f4fb5c39ea091aba0eacf6..9c2c4570169b7f82cb31b670dce69a78051d0b1c 100644
--- a/build/common.gypi
+++ b/build/common.gypi
@@ -3518,6 +3518,14 @@
         ],
       },
     }],
+    # TODO(thakis): Enable this everywhere. http://crbug.com/371125
+    ['OS=="linux" and chromeos==0 and component=="shared_library" and use_ozone!=1 and buildtype!="Official"', {
+      'target_defaults': {
+        'ldflags': [
+          '-Wl,-z,defs',
+        ],
+      },
+    }],
     ['os_posix==1 and chromeos==0', {
       # Chrome OS enables -fstack-protector-strong via its build wrapper,
       # and we want to avoid overriding this, so stack-protector is only