unix/Makefile.in: Update clean target to also remove the snes9x binary
unix/Makefile.in: Add a distclean target to remove autogenerated files
configure: Update configure script with autoconf v2.69
configure: Enable shared-memory support only if available
apu/resampler.h: Make the resampler destructor virtual

Avoids delete-non-virtual-dtor warning
port.h: Make READ_WORD a real function instead of a macro

Well, with some very limited exceptions (like MAX, MIN...), macros are bad.
Playing with pointer arithmetic can be fun but may backfire..
So let the compiler optmize your code and follow the standards.
By the way, this one fixes some -Wstrict-aliasing warnings.
port.h: Make WRITE_WORD a real function instead of a macro
port.h: Make READ_3WORD a real function instead of a macro
port.h: Make WRITE_3WORD a real function instead of a macro
port.h: Make READ_DWORD a real function instead of a macro
port.h: Make WRITE_DWORD a real function instead of a macro