[KPhotoAlbum] Build instructions have been updated

[Johannes Zarl-Zierl]

Hi Andreas,

> just a tiny bit (a small optimization):
> 
> use "make -jN"  with N = number of logical processors on your machine
> 
> This speeds up compilation drastically if you have a reasonably new
> machine (4 cores [N=4] or 4+hyperthreading [N=8]).

Good point. I've added this...

> I am building on openSuSE 42.2 using the same basic steps.  Only package
> management is different (with yast / rpm):
> 

It would be lovely if we could add openSUSE build instructions to the page. 
May I be so bold as to recruit you for this task?


> Having a new system, I usually iterate with "cmake ..".  This spits out
> one or more missing packages.
> 
> Search for the first missing package (and its "_devel.rpm") in yast,
> install, cmake, repeat until there are no more errors.  Do not use the
> 32-bit variants of the libs.

I'm actually doing this as well when I build unpackaged software (it's usualls 
the better method because it can't get outdated). In this guide, though, we 
tried to keep instructions simple and explicit.

Cheers,
  Johannes