[3.0.1, main] Installation documentation update for Sun

[Kelley Cook]

>> At the same time, I cleaned up the overall structure of the Sun section.
>>
>>        * doc/install.texi (*-*-solaris*): merge into ...
>>        (sparc-sun-solaris): ... here.  Eliminate redundant information and
>>        reword necessary packages section.

>I don't think that's correct, though: Solaris also has x86 versions,
>so *-*-solaris* is a superset of of sparc-sun-solaris.

Fair enough point.  I believe that all of the information is non-architecture
specific and should be merged into the same category.  Possibly the assembler
bug information is Sparc specific, but that is currently in the generic category.

Then again, though I do have a copy sitting on my shelf, I've never actually 
used x86 Solaris, so I'll defer judgement to you.

This file passed make info and looks correct under the info viewer.