This commit is number 3 of 4.

This commit is number 3 of 4.

In particular this commit focuses on:

Changing the Get_Pwnam code so that it can work in a const-enforced
environment.

While these changes have been mildly tested, and are pretty small, any
assistance in this is appreciated.

----

These changes allow for 'const' in the Samba tree.

There are a number of good reasons to do this:

	- I want to allow the SAM_ACCOUNT structure to move from wasteful
	pstrings and fstrings to  allocated strings.  We can't do that if
	people are modifying these outputs, as they may well make
	assumptions about getting pstrings and fstrings

	- I want --with-pam_smbpass to compile with a slightly sane
	volume of warnings, currently its  pretty bad, even in 2.2
	where is compiles at all.

	- Tridge assures me that he no longer opposes 'const religion'
	based on the ability to  #define const the problem away.

	- Changed Get_Pwnam(x,y) into two variants (so that the const
	parameter can work correctly): - Get_Pwnam(const x) and
	Get_Pwnam_Modify(x).

	- Reworked smbd/chgpasswd.c to work with these mods, passing
	around a 'struct passwd' rather  than the modified username