build: move libcc patches to electron repo (#14104)

In the GN build, libchromiumcontent is no longer a distinct library, but
merely a container for a set of scripts and patches. Maintaining those
patches in a separate repository is tedious and error-prone, so merge
them into the main repo.

Once this is merged and GN is the default way to build Electron, the
libchromiumcontent repository can be archived.

patches/common/chromium/ignore_rc_check.patch

@@ -0,0 +1,17 @@
+diff --git a/build/toolchain/win/tool_wrapper.py b/build/toolchain/win/tool_wrapper.py
+index a76e926a8681..c43839a01211 100644
+--- a/build/toolchain/win/tool_wrapper.py
++++ b/build/toolchain/win/tool_wrapper.py
+@@ -258,7 +258,11 @@ class WinTool(object):
+       if rc_exe_exit_code == 0:
+         import filecmp
+         # Strip "/fo" prefix.
+-        assert filecmp.cmp(rc_res_output[3:], rcpy_res_output[3:])
++        # ------
++        # Temporarily ignore compares
++        # Nightly builds use very large version numbers that fail this check
++        # FIXME(zacwalk): Enable the assert.
++        # assert filecmp.cmp(rc_res_output[3:], rcpy_res_output[3:])
+     return rc_exe_exit_code
+ 
+   def ExecActionWrapper(self, arch, rspfile, *dirname):