change "cpu" in cpu load backend functions
Merge branch 'master' into exportvis
Fix compile when using external version of libltc
Only use __declspec(dllimport/dllexport) for MSVC compiler

Use the gcc visibility attributes when building with the MinGW compiler(gcc).
GCC also supports the __declspec syntax but it will not compile at the moment
until the issues(which may not even be exactly the same issues as with MSVC)
are resolved.
Use the correct visibility macros
Remove old visibility.h header that is no longer in use
Remove duplicate use of LIBARDOUR_API from Session class
Merge branch 'expvis' of https://github.com/mojofunk/ardour into exportvis