[sldev] Making the build instructions better

[Rob Lanphier]

Hi all,

I've updated the build instructions on Linux:
http://wiki.secondlife.com/wiki/Compiling_the_viewer_(Linux)

I'd love to get some eyeballs on this, and see things get better there.

Here's the umbrella page for all platforms
http://wiki.secondlife.com/wiki/Get_source_and_compile

Currently, the page is split up into platform specific prep pages, and
then a general "CMake" page after that.  Michelle2's page is
consolidated into one big page.  Which is the better approach?

Rob