* exec.cc: Rearrange functions in alphabetical order.

	* exec.cc: Rearrange functions in alphabetical order.
	(_execve): Drop temporary define and drop export alias.
	(execl): Call spawnve.
	(execle): New function.
	(execlp): New function.
	(execv): Call spawnve.
	(execve): Drop converting NULL envp to emtpy envp.
	(execvp): Call spawnve.
	(execvpe): Drop converting NULL envp to emtpy envp.  Call spawnve.
	(fexecve): Call spawnve.
	* spawn.cc (spawnve): Convert NULL envp to emtpy envp.  Remove outdated
	comment.
	(spawnlp): Call spawnve.
	(spawnlpe): Ditto.
	(spawnvp): Ditto.
	(spawnvpe): Fix formatting.