net: Unbreak component build on Linux.

This is happening when running the following command line:

$ gn gen out/Debug --args='is_component_build=true'
ERROR at //net/third_party/nss/ssl/BUILD.gn:122:18: Item not found
    configs -= [ "//build/config/gcc:symbol_visibility_hidden" ]
                     ^--------------------------------------------
You were trying to remove "//build/config/gcc:symbol_visibility_hidden"
from the list but it wasn't there.

BUG=None
TEST=above
R=brettw@chromium.org,wtc@chromium.org
NOTRY=true

Review URL: https://codereview.chromium.org/285293009

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@271294 0039d316-1c4b-4281-b951-d872f2087c98

net/third_party/nss/ssl/BUILD.gn

@@ -78,7 +78,10 @@ component("libssl") {
     ]
     sources += [ "exports_win.def" ]
   } else if (is_linux) {
-    configs -= [ "//build/config/gcc:symbol_visibility_hidden" ]
+    if (component_mode == "shared_library") {
+      configs -= [ "//build/config/gcc:symbol_visibility_hidden" ]
+    }
+
     libs = [ "dl" ]
 
     include_dirs = [ "bodge" ]
@@ -118,10 +121,6 @@ component("libssl") {
     forward_dependent_configs_from = deps
   }
 
-  if (!is_win && component_mode == "shared_library") {
-    configs -= [ "//build/config/gcc:symbol_visibility_hidden" ]
-  }
-
   if (is_clang) {
     cflags += [
       # See http://crbug.com/138571#c8. In short, sslsecur.c picks up the