Add some information to Packaging cmake wiki

[Kevin Kofler]

Richard Shaw wrote:
> I've noticed with several packages lately that frequently the wrong
> build flags are used or appened to the ones the cmake macro sets.
> Sometimes this can happen because the main cmake configuration file
> forces the type to "Release" (bad!) but not always.
> 
> I've found that adding: "-DCMAKE_RELEASE_TYPE=RelWithDebinfo" often
> takes care of this.

FYI, some packages use bad flags with RelWithDebinfo and good ones with 
Release, some always use good flags, and some always use bad flags (and have 
to be patched).

(For example, the KDE packages are all built in release mode.)

It depends on the package. Always check the CFLAGS being used (the verbose 
build output).

        Kevin Kofler