gcc.c (_WIN32): Don't include process.h or declare spawnv{,p}.

gcc.c (_WIN32): Don't include process.h or declare spawnv{,p}.

	* gcc.c (_WIN32): Don't include process.h or declare spawnv{,p}.
	(pexecute,pwait): Add prototypes.
	(PEXECUTE_{FIRST,LAST,SEARCH}): Define.
	(execv,execvp): Delete decls.
	(perror_exec): Delete.
	(pfatal_pexecute): New function.
	(pexecute support): Delete.
	(execute): -pipe not supported if _WIN32 or OS2.
	Update call to pexecute.  Fatal error if pexecute fails.  Call pwait.

From-SVN: r12269