Update cogl.symbols and cogl-path.symbols

In Lionel's work for supporting introspection better for Cogl, a number of
public symbols were added for Cogl and Cogl-Path, so add these symbols to
cogl.symbols and cogl-path.symbols so that they can be exported, which will
fix the build of the Cogl conformance test and the introspection files
for the Windows-based builds.

Reviewed-by: Neil Roberts <neil@linux.intel.com>