Make the gyp files more cross-platform across the Unices

webkit/tools/pepper_test_plugin/pepper_test_plugin.gyp

Index: webkit/tools/pepper_test_plugin/pepper_test_plugin.gyp
diff --git a/webkit/tools/pepper_test_plugin/pepper_test_plugin.gyp b/webkit/tools/pepper_test_plugin/pepper_test_plugin.gyp
index 7f987bb63a8561aa37cc8c6c269227534a0854df..8c916863221576068f997268b5074ffe8cab9ed2 100644
--- a/webkit/tools/pepper_test_plugin/pepper_test_plugin.gyp
+++ b/webkit/tools/pepper_test_plugin/pepper_test_plugin.gyp
@@ -47,11 +47,11 @@
             ],
           },
         }],
-        ['OS=="linux" or OS=="freebsd" or OS=="openbsd" or OS=="solaris"', {
+        ['os_posix==1 and OS!="mac"', {
           'type': 'shared_library',
           'cflags': ['-fvisibility=hidden'],
         }],
-        ['OS=="linux" or OS=="openbsd" or OS=="freebsd" and (target_arch=="x64" or target_arch=="arm") and linux_fpic!=1', {
+        ['os_posix==1 and OS!="mac" and (target_arch=="x64" or target_arch=="arm") and linux_fpic!=1', {
           'product_name': 'pepper_test_plugin',
           # Shared libraries need -fPIC on x86-64
           'cflags': ['-fPIC'],