enable shared lib support in linux for lua

gyp/common_conditions.gypi

 # conditions used in both common.gypi and skia.gyp in chromium
 #
 {
   'defines': [
     'SK_ALLOW_STATIC_GLOBAL_INITIALIZERS=<(skia_static_initializers)',
 #    'SK_SUPPORT_HINTING_SCALE_FACTOR',
   ],
   'conditions' : [
     [ 'skia_gpu == 1',
       {
@@ skipping 122 matching lines @@
           },
         },
         'cflags': [
           '-Wall',
           '-Wextra',
           # suppressions below here were added for clang
           '-Wno-unused-parameter',
           '-Wno-c++11-extensions'
         ],
         'conditions' : [
+          [ 'skia_shared_lib', {
+            'cflags': [
+              '-fPIC',
+            ],
+            'defines': [
+              'GR_DLL=1',
+              'GR_IMPLEMENTATION=1',
+              'SKIA_DLL',
+              'SKIA_IMPLEMENTATION=1',
+            ],
+          }],
           [ 'skia_warnings_as_errors', {
             'cflags': [
               '-Werror',
             ],
           }],
           [ 'skia_os == "nacl"', {
             'defines': [
               'SK_BUILD_FOR_NACL',
             ],
             'link_settings': {
@@ skipping 261 matching lines @@
   'xcode_settings': {
     'SYMROOT': '<(DEPTH)/xcodebuild',
   },
 }
 
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