[ANNOUNCE] NSPR 4.8 to drop support of Windows 9x.

I have just created the NSPR_4_7_BRANCH for future
NSPR 4.7.x releases.  (The next one is NSPR 4.7.4.)

The NSPR trunk now has the version number 4.8 Beta.

NSPR 4.7.x will be the last NSPR series that supports
(or rather claims to support) Windows 9x.

NSPR 4.8 will only support Windows 2000 or higher.
This allows us to easily use the functions that are not
available in Windows 9x, without resorting to looking
up the functions' addresses at run time.

I will also rename the WIN95 build configuration:
https://bugzilla.mozilla.org/show_bug.cgi?id=476085

Ideally we should unify the WINNT and WIN95 build
configurations, but I don't have time to work on that.

Wan-Teh Chang