Build Skia as a static library

- Roll GYP so that we get non-thin archives on Linux
- Add merge_static_libs.py
- Add skia_core_lib target which builds core, ports, opts*, and utils
- Replace dependencies on core/ports/opts/utils with skia_core_libs
- Rename exportable libraries with "skia_"
Review URL: https://codereview.appspot.com/6619049

git-svn-id: http://skia.googlecode.com/svn/trunk@5889 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/tools/merge_static_libs.py b/tools/merge_static_libs.py
new file mode 100755
index 0000000..842be18
--- /dev/null
+++ b/tools/merge_static_libs.py
@@ -0,0 +1,66 @@
+#!/usr/bin/env python
+# Copyright (c) 2012 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import os
+import shutil
+import subprocess
+import sys
+import tempfile
+
+def _Usage():
+  print 'Usage: merge_static_libs OUTPUT_LIB INPUT_LIB [INPUT_LIB]*'
+  sys.exit(1)
+
+def MergeLibs(in_libs, out_lib):
+  """ Merges multiple static libraries into one.
+  
+  in_libs: list of paths to static libraries to be merged
+  out_lib: path to the static library which will be created from in_libs
+  """
+  if os.name == 'posix':
+    tempdir = tempfile.mkdtemp()
+    abs_in_libs = []
+    for in_lib in in_libs:
+      abs_in_libs.append(os.path.abspath(in_lib))
+    curdir = os.getcwd()
+    os.chdir(tempdir)
+    objects = []
+    ar = os.environ.get('AR', 'ar')
+    for in_lib in abs_in_libs:
+      proc = subprocess.Popen([ar, '-t', in_lib], stdout=subprocess.PIPE)
+      proc.wait()
+      obj_str = proc.communicate()[0]
+      current_objects = obj_str.rstrip().split('\n')
+      proc = subprocess.Popen([ar, '-x', in_lib], stdout=subprocess.PIPE,
+                              stderr=subprocess.STDOUT)
+      proc.wait()
+      if proc.poll() == 0:
+        # The static library is non-thin, and we extracted objects
+        for object in current_objects:
+          objects.append(os.path.abspath(object))
+      elif 'thin archive' in proc.communicate()[0]:
+        # The static library is thin, so it contains the paths to its objects
+        for object in current_objects:
+          objects.append(object)
+      else:
+        raise Exception('Failed to extract objects from %s.' % in_lib)
+    os.chdir(curdir)
+    if not subprocess.call([ar, '-crs', out_lib] + objects) == 0:
+      raise Exception('Failed to add object files to %s' % out_lib)
+    shutil.rmtree(tempdir)
+  elif os.name == 'nt':
+    subprocess.call(['lib', '/OUT:%s' % out_lib] + in_libs)
+  else:
+    raise Exception('Error: Your platform is not supported')
+
+def Main():
+  if len(sys.argv) < 3:
+    _Usage()
+  out_lib = sys.argv[1]
+  in_libs = sys.argv[2:]
+  MergeLibs(in_libs, out_lib)
+
+if '__main__' == __name__:
+  sys.exit(Main())