pcp

Changes to get MMV PMDA and library to build on Windows.

In particular:

• Use Win32 memory mapping routines on win32, mmap on POSIX.
• Use lseek+write instead of pwrite
• Dont initialise global variables to zero/null (cleanup)
• use system instead of fork+exec+waitpid
• use nanosleep instead of select-for-short-sleep

Also fix gcc warning about unhandled MMV_ENTRY_NOSUPPORT case.
Some path issues remain however, need to discuss how to fix up
those, esp in the ("standalone") library.